There are a ton of rides and atracations that children of all ages can enjoy at WDW. MK has the most but all of the parks have a few not to be missed things.
We took our DD for her 1st WDW vacation when she was almost 9 months old. The vacation was for us and it was a ton of fun. We even bought DVC that trip, and have been back 3 times since then. One warning, at age 2 they are old enough to ask to go back and our DD does all the time now. (she is 3 currenlty and our next trip isn't until she is almost 4, and her yet to be born little sister will be 6 months old.)
WDW is great for 2 year old, if you do it right and it sounds like you will. Plus they are free. Also all the "all you can get meals" are free at that age too.
Start off slow with rides that might scare him and work your way up. My friend brought her son on HM for the second ride when he was 2 and he refused to ride any others after that. Our friends wanted to try Buzz lightyear right away, it and scared their son (our DD was just fine) and it took him a while to relax. If you get the vacation planning DVD they have some ride atractions previews to get them ready, also an section on pre-schoolers in the parks. Make sure to bring a good stroller that folds up well for the bus.
Make sure to make time just to play and relax, there is a good play ground at MK in Toon Town, and a fun place near Spash Montain. THere also is a good one at MGM (honey I shurnk the kids) The dino Dig place at AK and Epcot has a number of fun places just to hang and play (The boat at Norway, the light up side walk in FL, the gardens at England ect...) Enjoy the down time, 2 year olds need a lot of it and they tend to have the most fun doing little things (but they love the rides too.) Make sure to hit Fansty Land at MK in the morning before it gets too busy and make the most of Fast Pass. Don't wait in any line over 35 min if you can swing it. It is just too hard on the little ones, and bring something to amuse them in line.
Consider a day at BB if it is warm enough, it has a great kiddy section for 2 year olds and the lazy river and wave pool are fun family things too.
Where are you staying? All the on prop resorts have some great things for young kids.
Have a good trip. Our 3 year old DD is now an WDW expert!