Depends if you want a single partner from incorporation to IPO, or if you just need some one-off legal advice while mucking around. I had a really good experience working with Carr & Ferrell on IP. Most of the bigger firms won't work with you if all you want is a proofread on some provisional patents. They were recommended to me by someone high up at Wilson Sonsini, and they did a great job.
http://www.orrick.com/practices/corporate/emergingCompanies/index.asp