Cheering for: Netherlands and Germany (I like their style), Italy and Czech Republic (I like their people), France (my wife is French), England (my family has, historically, been very loyal to the crown, and a Euro2012 victory would be a great story to go with the Olympics and Diamond Jubilee).
Cheering against: Sweden and Russia (I'm part Finnish), Republic of Ireland (also part Northern Irish), Spain (overrated, beat my Netherlands in WC2010), Poland and Ukraine (although I'm also part Ukranian -- gotta love being a North American mutt -- both countries seem to still have huge issues with racism and violence, so it makes it hard to cheer for them).
I know that's a lot of likes and dislikes, but for a Canadian with no obvious team to cheer for, its a lot easier -- and more fun! -- to be partially emotionally invested in many teams/games, than to be 100% behind a single team. After a quick check of the schedule, the only games I don't really care to watch is DEN-POR. Although, to be honest, most Group A matches are going to be pretty boring, style-wise.
Predictions:
Group A - CZE, RUS, POL, GRE
Group B - GER, NED, DEN, POR
Group C - ESP, CRO, ITA, IRL
Group D - FRA, ENG, SWE, UKR