For my money, I would go ahead and look at a small keelboat. I was in almost exactly the same position you are in last year at this time. I bought a 17' O'Day Daysailer. It's a great little boat, and there's a huge online community around these boats, both for racing- and cruising-related technical support. But, I had two gripes with the Daysailer.
1. It's an inconvenient size. It's too big to have any of the benefits of a really small boat (easy to handle on the hard, no standing rigging
, can be towed with a small car, etc.), but it's too small to have the big advantage of a larger boat, which is a usable cabin (usable for something other than stowing gear.)
2. It's not as stable. With just an unballasted centerboard, it was prone to knockdowns.
Neither of these are specific gripes against the Daysailer; they are applicable to any centerboard dinghy
in the 14' - 19' range. So as a result, within 6 months I had sold the Daysailer (at a handsome profit, due to good luck on my part), and bought a Hunter 18.5. It's not significantly larger at the waterline, but it has a cabin that sleeps two comfortably (four if they're all real
good friends), and it has a 500lb keel against the 1500lb total displacement, so it's more stable. The difference between what I sold the Daysailer for and what I paid for the Hunter was only like $600, and they were both less than $2,500. If you look around, I'm sure you could find a keelboat to match any dinghy
you'll find to well within 25% of the price.
So if it were me (and last year this time it was), I'd go for a small keelboat that you can go ahead and start weekending on now instead of a large centerboarder that you'll just be trading up later.
For what it's worth.