I would avoid Goodyear Marathons. If you search old posts you'll find glowing reviews about them, but that was from before they moved production overseas. Since then they haven't had many good reports.
Your current tires being worn on both the inside and outside may just be from under-inflation combined with being unbalanced.
You shouldn't need to do a complete bearing job. If you don't have oil bath hubs, just pop the hub caps off and pump grease into the end of the spindle until the old grease is forced out through the outer bearing. Might be a good idea to jack each wheel off the ground and wiggle the tire to be sure the bearings don't have excessive play, since you do have that tire wear.
If you have oil bath hubs, I can't help you.
