I've lived and sailed the great lakes my whole life, here are my thoughts on sailing the lakes.
Yes it is easier in some ways than sailing in the ocean, there are no tides to worry about other than seasonal variations in water level. There isn't the same swell, there just aren't 20 foot tall big slow low rollers. There are a lot of ports and a heck of a lot of other boaters out. That being said, the weather here is to put it mildly insane, not necessarily violent, just schizophrenic. You can never count on the weather farther out than about 20 minutes, especially on lake Superior. The waves can get big in a hurry and when they do they are very very steep. Some of the meanest waves I've seen have been on lake Superior on the west side of the Keweenaw Peninsula, coming from an arctic storm out of the NW. So if you look at your map, what I was seeing was probably way smaller than they were seeing on the very eastern end of the lake. Watch out for the waves! There isn't a "lot" of fetch on the lakes, don't get me wrong, even at their narrowest points you can't even come close to seeing across any of these lakes, but when a storm starts raising hell you can rest assured that almost invariably you will be either already very close to the lee shore, or you will come up to it very quickly. So, the relatively small fetch of the lakes is sometimes not a good thing at all.
Ok, so enough dire warnings and all that. The sailing is beautiful, most days you can wake up, look at what the wind is doing and find some place that is either a run or reach that is a neat place to go to. If you have never been to the Great Lakes, I would suggest visiting Northern Lake Michigan, and Northern Lake Huron, depending on your schedule. You can start at Traverse City, either by driving up from Detroit (4hrs) or Chicago (5hrs but a much prettier drive) or take a shuttle flight. From Traverse you can skirt north along the Leelanau Peninsula, stopping at Suttons Bay, or Northport two small resort towns known for their pinky-up stores and excellent wine and cherry products. Then across the bay to Charleviox, one of the most affluent resort towns in the country with a rich history and interesting shopping. Continuing north to a last stop at Harbor Springs before an overnight passage up and around the tip of the Lower Peninsula of Michigan, under the famous Mackinac bridge, one of the longest suspension bridges in the world to Mackinac Island.
The island is an interesting piece of history, originally a fortress, the island does not allow motorized vehicles and so all business is done by horse or bicycle. You can bike around the island, visit the historic fortress, and if you are feeling up to a night of old school class stay at the five star Grand Hotel. If you have about 10 days, this would be a good place to turn around and head back hopping over the cities already visited.
If you have even more time you can keep going up to the village of De Tour, this is where you have to make a decision, Lake Huron or Lake Superior, Superior is vast stretches of empty water and shore with very few boats or inhabitants and very few protected harbors, but scenery that can't possibly be captured on film and solitude that has kept me up here through six (very long) winters. Huron and the north channel is warmer and much more populated and has many boaters out on vacation throughout the summer. The north channel is a series of islands that skirt the northeastern shore of lake Huron.
If you are very short on time, and want a beautiful escape to nature, fly into Manitoulin Island and grab a charter boat on the island, and from there explore the thousands of tiny islands and harbors. One warning about north channel, it is very rocky with enormous boulders poking up everywhere, you can run into them very easily so watch your charts.
If you are in for a more remote experience sail up through Sault Ste Marie and head up and around Whitefish point, where the legendary Edmund Fitzgerald, a 730 foot long iron ore cargo ship broke apart and sank with all hands. Keep heading west until you are alongside Pictured Rocks National Lakeshore, this area gives you a beautiful view of the Jacobsville Sandstone cliffs that are so beautiful they have been quarried and shipped as far as New York to be used as cladding on government buildings, churches, and museums. The Lakeshore is bounded at either end by safe harbors at Grand Marais and Munising, but be warned the "yoopers" as locals are called though incredibly friendly are nearly 8 hours from the nearest large city and endure some of the roughest winters around so they take quite an interest in drinking and not much else, so if you are looking for culture, here is not where you will find it.
If you are truly adventurous you can keep going west to Marquette and then up and around the Yellow Dog Plains past the Huron Mountains home of the Huron Mountain Club, a semi-secret vacation resort for the old-money families of New York. This exclusive club has an enormous land holding and armed security patrols its borders. Westward still leads to the Keweenaw Peninsula, my current place of residence. This spit of land best known for its history in copper mining is rugged landscape with towns that boomed and have now bust. The area is now home to outdoor adventure lovers of every kind. Travel through the canal stopping at Houghton for a bit of culture and a lot of very good microbrewed beer (we have 4 breweries). You can travel north to Isle Royale or west to the Apostle Islands. Isle Royale is one of the most remote national parks, closer to Canada than the US the park is home to wolves, moose, and innumerable wildlife. It is an easy hop from the island to Thunder Bay. The Apostle Islands are set of small islands that locals enjoy day trips to picnic on and enjoy beautiful scenery. There are several large towns nearby, Bayfield, Washburn, and Ashland. In both Bayfield, and Thunder Bay, there are sailboat charters if you wanted to start from here, but again, lake Superior has by far the most dangerous weather so be warned.
To sail all the way from Traverse City to Bayfield would take about a month, not to mention the return trip. On the plus side return trips are made much more interesting by switching shores of the lake so that you don't ever see the same thing twice. My apologies to Door County, the Garden Peninsula, all of the beautiful towns on southern lake Michigan, and lake Huron, and all of Erie and Ontario for not being included in my little tour. This is what I would do if I had all summer and wanted to take a very long cruise, this trip would probably take around three months round trip accounting for weather and other unforeseen events.
Well, I hope that kind of helps and I encourage anyone that likes water to come and visit the Great Lakes, remember, we have more shoreline than the entire rest of the United States all packed into one small area so there is no limit to the amount of things to do.