You can also add rackspace on top of the list, though many of these companies will try to lock you into a one year contract, which I would advise against. Try running month-to-month so in case there's any issue you can just move away at any time.
Are your servers Windows servers only, or are you also running Linux? Do you have any special needs like firewalls, DDoS protection?
High Bandwidth Servers
Custom Hosting Solutions
are you looking for a specific area in the US, Northeast, Southeast, West? Also what kind of budget are you under? Also make sure when looking at managed solutions, that you fully understand what the host means by managed hosting? Is it a fully managed solutions, or a semi managed with a control panel.