Plan my vacation

I have some down time between the start of my clerkship (the day after Labor Day) and the bar. I am attending a friend's wedding in Indiana on the 13th of August, but when I fly out on the 14th my schedule is open. The only restrictions are:

-I want to spend a few days in Houston with family before I move to Clerkshipsville, which will probably happen on the 25th or 27th of August or thereabouts (my dates are somewhat flexible).
-My stuff is in two large suitcases, a carryon, and three cardboard boxes. If I go on a trip I can probably take the carryon or the smaller of the big suitcases but will need to ship the rest to Houston. Can you ship a suitcase UPS?
-I have already been to most of Europe, including Spain (not pictured), although Ireland is appealing. I have been to Iceland, but not in the summer. I am not much for beaches when I am traveling by myself.
-I read A Supposedly Fun Thing I'll Never Do Again and am somewhat skeptical of cruises, if still slightly curious.
-I have never been to Canada or Mexico.
-My idea of a good time includes art museums, hiking along ancient historic trails, and eating delicious food. It does not include getting a bad sunburn or contracting Third World diseases.

Any ideas, readers?

UPDATE: Lots of good suggestions. Further input from me: I was thinking of about a trip of 5-6 days. I will be traveling alone, so if some places might be uncomfortable for a solo woman traveler who only speaks English, keep that in mind. Baltic cruises sound fun but like they might be too long. I have been to Eastern Europe.
Mexico: I have a cousin in Merida who has been badgering me to visit for a dozen years now, but his wife just had a baby and so he's probably busy.