Hi I am shooting a commercial spot for local cable I like to have your thoughts on shooting with XL2 in 30P mode, or do you think it is better to shoot 60i. Thanks

It's an aesthetic choice. Use whichever look you prefer. I've shot many spots on the DVX in 24P to get that filmlike look.

It doesn't matter for airing, since the format in the end is the same.
As Barry indicated, it is an aesthetic choice, go with the look you
and the client want for the commercial. If it is supposed to look
realistic shooting in interlaced might be better. If you are going
for a movie look 30p or 24p (in 2:3 normal pulldown mode) might
be a good choice.