What about Cape Town, South Africa? It's a long haul but easier to handle coming from the east coast and definitely a place you want to have 10-14 days in considering the length of the flight. Weather should still be good in mid-March. Getting to Europe from the west coast is still relatively easy, and not that much longer than flying from NYC if you go direct. Seeing fares for about $1,100 per person with 1 stop in Europe.

$800 to Spain seems like a good deal, and the weather will be pleasantly mild. It gets stifling hot in the mid summer. With 2 weeks you could see 2-3 cities.

You rule out the Caribbean, but I think it might be a good option too if there's anywhere in particular you've been wanting to visit. As a west coast traveler, we typically avoid the Caribbean islands because of how long it takes to get there. It usually means taking a red eye or arriving at the destination very late and wasting a paid night at the resort. Because of that most of our warm tropical vacations are to Mexico or Hawaii.