If you've never been outside the U.S., I'd say stick with something basic so as to get your feet wet with international travel for more adventurous trips later. European destinations are generally a good way to start off but it's very expensive right now as others have pointed out, and March is generally still a bit on the cooler side even in the southern cities like Nice and Barcelona (average highs in the upper 50s).
If you're both the very adventurous, fearless type that first-time travelling wouldn't faze then some alternatives to a standard Eurotrip might be Peru (go see Machu Picchu while you still can), Morocco, Uganda (safari), South Africa (ditto on the safari), or even Beirut, Lebanon (take a side trip to Jordan to see Petras while you're at it). All more expensive than a package 7-day NYC-London type of deal but also much more interesting.