We'll be visiting Orlando for a week next March. We'll be mostly doing Disney but we'd like to take one day and do something else. We've already done the Kennedy Space Center twice and have explored Cocoa Beach. We're considering Tampa or Daytona Beach (but not interested in racing stuff) or maybe St. Augustine although that might be a little far. Our group is 4 adults.

How about Winter Park? It isn't exactly a day trip as it is basically in Orlando, but it's a town with a unique vibe for Florida. And there is a really excellent museum of Tiffany stained glass. It might be tough to fill a long day there, but you could do the museum, eat lunch, check out a few boutiques, have a pastry at the French bakery whose name I forget, drive or walk through the neighborhoods with historic bungalows, and have dinner at The Ravenous Pig, a famed gastropub.

St. Augustine is a half hour further than Tampa. If you go to Clearwater or St. Pete, it's the same distance. St. Augustine has the historic fort, nice restaurants, and the Sawgrass Mills if you aren't already shopped out.

Tampa has Ybor City that includes the Columbia Restaurant, Busch Gardens, and the Gulf beaches.

There's also a barge trip through the canals in Winter Park that's very enjoyable, taking you past some of the old homes, out into the lake, and back.

If you do Tampa Bay area, I'd make the drive to Ft Desoto for beautiful, unspoiled beaches...no hotels, no restaurants, just the dunes, long stretches of beach and you. There's an old fort there and snacks in that area. Further north on Ft Desoto there are more dressing areas/rest rooms and picnic tables. You can also rent kayaks. It's a beautiful stretch of beach, away from the hordes that crowd the Clearwater area. Desoto was named by Dr. Stephen Leatherman Best Beach in the US for 2005. http://www.pinellascounty.org/park/05_Ft_Desoto.htm I love that there is ample parking out there and it is very inexpensive. You pay the entrance fee only which is ridiculously inexpensive... $.35 last time we were there, then no fee for parking. You'll need your own towels/chairs.

Great idea, NewbE. Adding that you could also go on the Winter Park boat ride (a pontoon boat ride through the chain of lakes - scenicboattours.com/ ), visit the art museum on the Rollins College campus or the Albin Polasek museum (http://polasek.org/).

St. Augustine is worthwhile. Tour the castillo, take a walking tour, shop, and eat at any of the really good restaurants.

Great minds OO! Love that boat ride!

St. Augustine is about 100 miles (2 hours). Around Daytona (1 hour), you may enjoy a drive to Flagler Beach. Or, you may want to go the opposite direction to New Smyrna Beach. Bethune Beach is further south. However, that area is very laid back. Do check the weather before you go because the east coast could be quite windy in March. Melbourne Beach (1.5 hours) could be a little warmer but I have not been for years so am not sure what is going on there these days.
If you head west towards Tampa, and like art, I think Salvador Dali, in St. Petersburg is definitely worth seeing. And, it is a nice area to explore.(2 hour drive on a good day). Another pleasant option could be 'Silver River State Park' near Ocala which is one of the nicest parks in Florida (1.5hours).

Wow, what great suggestions! Thanks everyone. Off to research these ideas.

Skip Daytona. It's overrated IMO.

321go and 00 are giving you good suggestions. Winter Park's Scenic Boat Tour is a very nice and relaxing look at some gorgeous lakeside scenery. I agree with NewbE's suggestion about dining at the Ravenous Pig!

St. Augustine is equally worthwhile and has much history, art galleries, uncrowded beaches and many good & reasonably priced (non-chain) restaurants. The distance is 90-100 miles (depending on starting point) and 2 hours by interstate highways (I-4 & I-95), so it would be an all-day trip. Here are a few links:

http://www.staugustine.com/visit/
http://www.visitflorida.com/St_Augustine
http://www.getaway4florida.com/

You can't go wrong with either choice.