Hi! I would first begin working with open cup and straw drinking. I use yogurt drinks, baby food puree mixed with formula, milk, or water and sometimes powder pudding mix for beginning cup drinking. Thickening slows the flow allowing some independence while learning as well as practice with lip closure. You can gradually thin the liquid as he becomes more efficient.
As far as sippy and transitional cups, I like this one without the valve, playtex tumbler....http://www.amazon.com/Playtex-Coolster-Tumbler-Sippy-Girls/dp/B0011E4HBM as it is similar to open cup and does not require as much suckling when valve is out. Also the toss and go cup he was using at school was fine too as well as straw cups...You should allow him opportunities for open cup drinking and sippy without valves. The suction required for sippy cups, especially with valves, often results in the same suckle pattern with manipulation of foods requiring a consecutive lateral munching pattern. I also like this one: http://citikids.com/ProductImages/24026.1.jpg I forgot about those! I need to get those for my daughter for school :) That was Munchkin brand and so is this one: http://usera.imagecave.com/loveski777/Munchkin%20Dora%20Big%20Kid%20Cup.jpg You can also take valves out of this one as well.
Here is a link to a great article by Melanie Potuck related to this blog topic:
**The cup options are plenty, overwhelming at times and since the original date of this blog there have been numerous changes including discontinuation of cups, new products and other options. I'm including some pictures as examples of some cups currently available! My go to practice cups in therapy are still often the very basic open cup with a thickened liquid to slow the flow and straw practice! I love the spoutless options available and you can never go wrong with the basic disposable coffee cup and lids that you would receive at most restaurants, drive thrust or find at the store. I recently bought a cup at the dollar tree (also pictured). My oldest daughter has claimed this one as you can see by the artwork :). Tervis lids are also ideal.
Please feel free to Share your finds! A child who is having a lot of difficulty transitioning from bottle to any other cup is a different scenario in my opinion. Often the anxiety is very much escalated at the idea of any new presentation and in those instances and other child specific examples, there may be acceptance of the silicone sippy cups and straws and this can open the door for other changes to take place! It's difficult to cover all of the challenges and different scenarios in one post, but finding what you have to work with is essential and taking things one step at a time to reach the long term goal is often the key to success!