Dedicated Servers & Colocation - Major Players

I was a webhost from a while ago leasing dedicated servers and eventually went to work for the datacenter where I had my colo. For a while now I've working with a neat group of 5-6 other folks programming a new uptime monitor/geo-dispersed server load testing system/software. We were looking for possible partners to keep hosting costs down during the alpha stage of the project but while we were drawing up the papers, we saw just too much opportunity for a conflict of interest to arise and realized we couldn't realistically associate ourselves with any single company to that degree. So after a little work and fundraising, we're finally in a position to either lease some servers or colo.

Since I've been out of the loop for a while, I just want to know who the major/reliable players are when it comes to leasing or colo machines in multiple areas (ideally East, Middle, West, Canada and Europe/Asia? We would prefer to be with one company for ease of billing and have our network of monitoring stations spread out geographically. But we don't want all of our eggs in one basket so if a provider goes belly-up or decides to hike our rates 30-40% with little notice, we won't have too much to worry about.

We're watching what we spend during the alpha stage very closely, but I've been insisting we can strike the right balance between cost and reliability (connectivity).