Danny, the wife and I have been there several times. Here is a couple of sites with everything you want to know (and then some) -
//www.catalina.com/catalinahome.html Catalina Island Vacation Guide. We stayed at the Villa Portofino Inn last time we went (last March)-
The Villa Portofino Hotel on Catalina Island - It was very nice, right on the waterfront. There are lots of nice hotels in Avalon, just depends on where you want to be, what kind of view you want, amenties (hot tub in the room etc.) and the budget you are working with. Pretty much everything is within walking distance no matter where you stay. We took the Catalina Express from Long Beach. Definitely get the upgrade to the captain's lounge, its upstairs for a great view and cocktails are available ( I always look out for the essentials).
Not a lot to do, but if you want to just relax and spend time with your significant other its great. I wouldn't recommend it as a family trip, though. The Fish and Chips place on the Green Pier won't be open until April or May which is a shame because it's great. I don't think the Descanso Beach Club is open in March either. Marlin Club is a pretty cool old school bar. Luau Larry's is a fun place to hang out. Steve's serves a passable steak and has pretty darn good service and it does have some killer views from upstairs. El Galleon is not bad either and they have pretty damn good margaritas too. The restaurant at the Villa Portofino was probably our favorite, but then again I'm Italian by marriage. Most of the restuarants are pretty good (nothing there that I would really rave about). We've eaten at most of them at one time or another and never had a bad meal, but never been blown away either.
March is not very crowded, after the last boat leaves its almost deserted. If you are looking for a very relaxed weekend and some time to yourselves, you will have a great time. March can be pretty cold/windy at Cat so be sure to bring some warm clothes.