The search is over!! Don't know if anyone cares at this point, but we've found the stand we are going to get. I'm not sure if this is the site we are getting it from, but here's a link Stand
BTW...I love how much easier it is to put in links since the boards were upgraded.
Anyway, we looked at bigger units, but decided in the end that we didn't want to switch what wall everything was on. The furniture would not fit in the room as well and we'd only be about 8 feet from the TV, which might be ok for some, but when you factor in that we are about 12 feet now and the TV will be much bigger, we decided against that.
A new stand might still be in our future when we move someday and have a different room to play with, but this is it for now. The stand will hold the 50" TV no problem. I'm not sure about the 55". Depth on the 55" is 18.9, the stand is 18.25. I would assume the base of the TV is not actually 18.9, so it might work. I'm pretty sure the 60" won't work, and don't think I want to go quite that big anyway.
Thanks for everyone's help throughout the process.