Ymmv!

Depends on your chemistry & devotion!

Experience #2 is more common in the lifestyle world.  Experience #1 is what you'd be more likely to encounter in a professional domination situation where some sexual stimulation is provided (but not all dominatrixes do that!).

Spanking is a wonderful warm-up for additional BDSM play, and many women can be rocked to orgasm from spanking.  It's a little bit more difficult to do with men, but we have a spot that stimulates the prostate if spanked.  It's entirely possible that you had a bad spanking partner . . .  I've run into some play partners who are wonderful at it, and others who are just into giving pain and/or simply don't know what they are doing (i.e., striking the same spot repeatedly, not giving a proper build-up, etc.).

Sometimes, it's more comfortable to be over just one knee, and the spanker can lower the other leg, so that the position itself doesn't compress the spankee in an uncomfortable way.  If you have a spanking bench (horse) to play on, that's even better.

OTK is possibly my favorite !!

I like across the lap, with the bottom's cock trapped between my legs, but I think my favorite way is over one knee, with my other leg locking the bottom's legs down. I find it be a tad more intimate, with more body to body contact, and it allows for some squirmage against my thigh