Re: Sailing alone??
Your wife may be more comfortable, and thus be more willing to sail, on a larger keel boat. It has more conveniences, generally dryer, more comfortable, stable.... My wife loves to sail, but her helping out means she takes the wheel if I need to go up front for something. I also do sail alone quite often and as long as your sheets run to the cockpit, it's no problem at all.
All that said, there's nothing like learning to sail on a little dinghy. But depending on your wife, it may not be her thing.