Most of the "turkey calculators that I'm finding say that for 8 people, you're looking at an 8-10 lb turkey. If you want left overs, you're looking at a 12+ lb turkey or turkey breast. I don't think a turkey breast is really any "easier" to fix than a turkey, it's just smaller. So, if you're fixing it and you like left overs or someone at your table likes dark meat, I'd stick with a turkey. If you only really like the white meat and can find a large enough turkey breast, I'd go that route.
-Kris
DS (9/05)
DD (8/08)
DD (9/12)