St. Louis isn't the easiest place to get around without a car, but Schlafly's Tap Room should be doable for you. Also check out Four Hands, not far from Busch Stadium.
Plan your AB trip ahead of time. They changed formats a few months ago, and I haven't been on the new one. It used to be really impressive. The new one that's free is supposed be be shorter, but they've got a longer non-free one as well. The Post has an article about the changes:
http://m.stltoday.com/business/local/a-b-tweaks-free-brewery-tours-adds-day-fresh-tours/article_81df0e7c-9975-501c-9640-26251e4fa4bf.html?mobile_touch=true Hair of the Dog on Washington has a decent beer selection, and has a bit of a dive feel to it. They are not that far from Alpha Brewing, which honestly isn't my favorite place, but it will be close to you.
If you can manage a trip out of downtown, definitely check out Perennial and Civil Life. There's a new bottle shop in Clayton called Craft Beer Cellar that has a good selection and will break up six packs. The new Urban Chestnut location on Manchester is worth a trip. If you find yourself on LaCledes Landing, skip everything else and go to Morgan Street. They have a couple of good lagers there.