Try a Gel Pad. I have been using Ultimate Low-Rider seats on both my 02 and 03 VTX1800R for a combined 60,000 miles. The seats are great, but the 1/2" thick gel pad adds another layer of ass comfort.
03 1800R (purchased in Texas in 2013 with 20,000 miles), Spiegler brake/clutch line kit, custom paint job by BD's Cycles from North Carolina, Mussy 2 into 2 exhaust, PCIII, Hypercharger Pro, Ultimate Lowrider seats, Edge extra large saddlebags, Clearview +4" windshield, Aeromach 6" risers, Uniq Cycle Sounds speakers, lots of Kuryakyn chrome, NC Paladin engine guard, etc. "Always Expect the Unexpected"