I am tall and have bad knees; therefore, I am looking for a new comfort height toilet, but it needs to have a rounded front--not elongated. Any suggestions for toilets with the highest seat bowls on the market? Also, can you recommend the thickest toilet seats available? Thanks!
Gerber's Ultra Flush (pressure assist) is available with an ADA-compliant round bowl.
American Standard's models available in ADA round bowl are: Triangle Cadet 3 and Triangle Cadet PRO (corner models); Champion 4 Max; Renaissance WaterWarden; Cadet 3 Flowise w/concealed trap; Mainstream; Champion PRO; Cadet PRO; and Cadet 3. Pick of the litter here is the Cadet PRO.
Cadet 3 Flowise w/concealed trap
Kohler's Cimarron and Memoirs toilets are also available with your specifications.
From my personal experience, Kohler models without pressure assist (such as those listed above) and Toto models without Double Cyclone are lacking in bowl rinse above the bowl's water line. The same is true for American Standard's without the PowerWash rim, which is a feature of their PRO line, among others.
As for the height of the actual toilet seat, you'd probably be best served to go to one of the home stores (Lowe's, The Home Depot, etc.) for a visual comparison.
I hope this helps.