I tried the Cisco Assessor lab from Labgear, Technology Networks, and found it very interesting. The userinterface is not really good and makes things quite difficult, but if you want to get an idea on how it could be in teh lab, this is a good starting point.
I did both labs and the secound lab also has four siwtches in the topology. Also the mixture with 3550 and 3560’s.
There is an AutoVerify you can run during the session to watch, if your answers have been correct and which part of the questions haven’t been or what is missing still.
After the four hour lab, you have two hours to check the solutions.
More details:
http://www.cisco.com/web/learning/le3/ccie/preparation/assessor_details.html