Hmmm... I think there are a few questions which need to be asked before we can really give you sound advice; some of these have been mentioned above.
1- Do you prefer to try new places each trip, or is there a destination that you like to frequent? Are you looking to constantly go new places, or do you like the idea of a familiar destination to travel to perhaps half the time?
2- Are any of the US destinations within reasonable driving distance?
3- What is your work flexibility? What is your personal flexibility (os- are you locked into school vacations and, if so, will that likely change in the near future)?
4- Are you ok with week long vacations, or do you prefer shorter stays (or only like longer stays)?
5- Budget is always a consideration....
For example, as Littlestar points out, many here love resale weeks at Grande Vista for either use or to trade in II, but you either have to like Orlando (and many people do) and/or have the flexibility to obtain trades in II. You are less likely to do well in II if you have a more restricted vacation schedule and can only travel high demand weeks, but if you have wide personal availability and/or can travel slightly off season, II can be amazing value-wise. Another consideration is if you really enjoy a certain destination, and envision returning most years. then buying a week there on the resale market is likely your best option. In our case, we love Aruba, so owning there makes sense for us. We have job flexibility, so trading in II has worked well for us. Anyway, as you explore your options, these are some factors to consider.
Good luck!