I think most people would like to see the PT duels look more like OT ones but Mark Hamill frequently asked if he could use different fencing styles and was told by Lucas that lightsabers don't work that way (always in motion is the future, the past....).

It would be very difficult, if not impossible to do convincingly (just look how fake some of Dooku and Sidious' acrobatics look) and to pull it off you'd possibly have to stick Mark's head onto someone else's body.

It would be easier to do with Vader but only a little bit, unless you removed him altogether and replaced him with a double in a suit and matched it perfectly (something else they couldn't do in the PT).

Beefing up the ground battle is much easier and there are plenty of suggestions on this thread for how to do that.