how many cores are you going to have in your Physical host? if you have a large amount of cores ie one of the new Quad way /quad cores servers then you may be able to have enough resourses available to guarantee the 4 cores needed to run a 4vCPU server,
personally I would go with serveral lower spec Guests and spread the SQL load amounst the Host Farm. that way you would not be running into CPU scheduling issues.
Tom Howarth
VMware Communities User Moderator
Tom Howarth VCP / VCAP / vExpert
VMware Communities User Moderator
Blog: http://www.planetvm.net
Contributing author on VMware vSphere and Virtual Infrastructure Security: Securing ESX and the Virtual Environment
Contributing author on VCP VMware Certified Professional on VSphere 4 Study Guide: Exam VCP-410
