Patty,
I personally would upgrade, provided it won't stretch your budget too tightly to enjoy other things. I think the amenities change pretty drastically between value and moderate than they do between moderate and deluxe, and the resorts have a different feel to them.
You mentioned my two favorite moderate resorts, but of the two I would definitely pick Caribbean Beach. This resort has just been extensively renovated. The rooms are all new, with either Finding Nemo or Pirates of the Caribbean themeing. I had the opportunity to tour a few weeks ago and I was very impressed. The pirate rooms especially will be very popular!
Also very exciting for this resort is the new pool, which in my opinion rivals those at deluxe resorts. It boasts a zero entry area, two waterslides, and numerous fountains. The kiddie pool is now also zero entry, and features a pirate ship to play on and a baby waterslide of its very own. I believe that this new pool will be a big draw to this resort. I know my family wants to stay in a pirate room and check it out!
If you'd like to see detailed pictures of the pool and the rooms, visit
www.disunplugged,com and search 'caribbean beach pool'. The first few results that come up will have great info for you!
Have a wonderful vacation!