I've heard that the Walgreens/CVS brands are just fine. If you don't choose those, at least select a brand you have heard of before. It does make a difference.
I just use the generic version of Flintstones vitamins. Not flashy, but relatively inexpensive and chewable, and seem to stack up fairly well numbers-wise with the pricier adult versions. I hate swallowing pills, so these chewables are great. I definitely feel better later in the day when I've taken then versus when I haven't.
back in the days I used Universal Nutrition's Animal Pak they come in a box and are individually packed... it brings 44 packs and should last you a little over a month... taking one pak a day...
but I recently picked up Costco brand Kirkland Multi Vitamin Pack it brings 100 packs for 13 dollars with a coupon from Costco
From my research it doesn't help or hurt to take a Multi-Vitamin. So to be on the safe side I take "one a day". Good point about iron. Men generally have to much iron in their blood.
As for other supplements, fish oil. The research is overwhelmingly in support of the benefits of fish oil.