We use Softlayer too for the same reasons. Have been with them for over 10 years now - since they were called The Planet. Just had one hardware failure during the entire time. They also now offer Cloud computing instances - which can be deployed either hourly or monthly. And you can mix and match your Cloud and dedicated servers - giving you all the flexibility to scale that you get with AWS / EC2.
Our own experience with their Cloud offering is more recent and a bit different. We have been using cloud computing instances running Haproxy as load balancers to route millions of requests to multiple physical web servers for over a year now. Can't generalize - but we have had no problems so far.
