I think the remaster was much better for Monkey Island 2 than for 1. So for MI 1 I'd go for the original look, but the remastered edition includes it too, you just need to press a button to change. I know some people have found out a way to play a "talkie" version of MI1 with the old graphics, you can check that out. I think it doesn't require much tinkering.

MI2 has a much more polished remastered. But the original pixel art is beautiful too, since you don't know it, get the remastered version and change between one and the other (again, the old one is included; MI2 does have voiceover in the old version).