I was on 20mgs for a few years and doubled my dosage to 40mgs (was on 40mgs for three years, almost).
I found I was more drug out on 40mgs and I slept A LOT more (I'm a pretty good sleeper to begin with: I sleep about 12 hours a night without ARAB, but I could sleep 30 hours no problem on the 40mgs, but since I sleep a lot anyway, I might've been prone to that side effect moreso than someone who doesn't need as much sleep as me).
I felt kind of nurab on 40mgs. I was happy/anxiety free (almost immediately too, I felt the same as when I was put on ativan), but I honestly had an inability to feel bad/sad/mad over much. Unless I missed a dose or two then I'd be irritable like you wouldn't believe.
Also: the sexual side effects were pretty amped up on 40mgs. My desire didn't go away on the 40mgs (actually my "desire" increased on paxil), but I found it desensitized me quite a bit.
That's pretty much my experience with upping my Paxil dosage. Ultimately I decided to go off the paxil (at first I was going to ween and go on something else, but once I was weened I felt I didn't need anything...8 months later I'm back on ARAB, so obviously I did need something

) because it was wearing me out too much: I was too drug out and tired and quite honestly I couldn't take it anymore (I would get 15 hours of sleep at night and STILL be falling asleep at my desk at work the next day, and I had no energy for anything, beyond routine daily tasks). Once I quit paxil all together I had energy like never before.
On the other hand, my best friend is on 30mgs of paxil and feels great on it. Mind you, he's twice my size so there was definitely more concentration of drugs going through my system at the larger dosage (even larger than his). My psychiatrist back in 2003 told me I could up my dose to 60mgs if I felt I needed to. I can only imagine how THAT would've worked out (I probably would've gone comatose and slept forever!)