Braintree is expensive when you're just getting started. Their API is nicer than authorize.net's API, but if you're using a service like Spreedly, it's Spreedly's API you'll be talking to, not Braintree's.
I haven't spent much time looking at PayPal's API, but it looks like that more of a competitor to something like braintree or authorize.net. It's just for processing the payment, right? The services I'm looking at here manage the entire subscription process. Essentially, you're outsourcing your billing system to them so that you don't have to think about things like dealing with the dunning process or prorating the bill if the user upgrades their plan mid-month, etc.
I don't know if I should have emphasized this more in the original post, but 11/17 is next Tuesday, not today. :) I wanted to give everybody a week's notice to make plans.
Jake, I'm glad you did ChicagoTechCal. I've been meaning to do something like that ever since we had Chicago Startup Weekend overlapping Flourish Conf, and only a week after PyCon. I'm sorry about the overlap; Chicago has at least one person going to interview at YC, and we wanted to have the meetup before he leaves on Wednesday morning. We've already announced Tuesday night as the next meetup, so we should probably leave it, but we'll check the calendar next time to avoid an overlap.
+1. If you wanted to geek out or maybe demo something you're working on, Sully's Pub near North and Halsted might work. Chicago's Python and Android groups have met there a few times. They have a room upstairs with wifi and a projector, although I'm not sure if you can use that room unless you have a ChiPy-size group to buy enough food and drink.