Typically the most popular spots are along the 1st and 3rd base line, further out you go the worse the seats. Or behind home plate.
Really depends on how much you want to spend too.
I don't know if this will link properly, it is the ticketmaster map of skydome.
http://www.ticketmaster.ca/event/100..._Tickets-na-x0
I'd go for anything between sections 129 to 114.