I'm still haven't heard from Maryland either, so I guess I am on a de facto waitinglist. Rejections are starting to pop up on gradcafe so I'm assuming that as first rounds accept, they start rejecting people that were on the bottom of the waitinglist. Frankly I am not holding my breath on them. I was actually waitlisted with Northwestern, as in they called and told me what was going on. They actually seemed to care about my application.
Assuming you do get an offer, I'd say if you want to go into Academia/National Lab then go with Maryland. There is a large enough gap bewteen the two on rankings, as far as I can tell. Applied Math rankings are just terrible and spotty. Plus if Maryland gives funding it should be a significant more that Colorado's offer.
I'd say there are two reasons to choose Colorado. If your research interest are represented at Colorado and not at Maryland. Also if your significant other just flat out doesnt want to live in Maryland for whatever reason.
Good Luck and Thank God this process is almost over.