D.M.
The only brand that has worked for my 3 yr old & 16 mo old are the PLAYTEX SIPSTERS. When I got both of them to drink water or juice from a sippy cup, these are the best! I used the smaller size when I was training them. I think they are a 6 or 9 oz size. The only place I could find the smaller sized ones for little hands were at BabiesRUs. I just moved my 16 mo old to the larger version, it's taller & holds more. I think its a 10 or 12 oz cup. TARGET sells these. I wouldn't worry about straw cups yet for an 11 mo old. I think you have to go 1 step at a time. Straw cups for that young of an age tend to be messy--maybe just use them at home but use the sippy when you go out. My 16 mo old still takes her bottle of milk at her nap time or at bed time. Otherwise, she only uses a sippy for juice/water. When she's ready to give up the bottle, she'll let me know. My 3 yr old refused his bed/naptime bottle at about 17-18 mos.
D.