I will not go into great detail about these, but a couple of things you might consider
There is a very good chance that tax rates will go up in the future .. so paying now might benefit you in the long run.
You can convert this year .. no income limitations .. and you can elect to pay the tax in 2011 and 2012 .. do a deferral of the taxes, tho with interest rates so low, doesn't mean much.
If you convert and want to hedge your bets a bit, open more than one ROTH account .. my broker allows as many as I need .
Then put different styles of investment in each..
for example, you might have one with emerging markets ETFs ..
another with just Apple stock ..
another with just REITS
Why you ask?/ if you don't file your tax return (don't for get to get an extension) until 10/15/2011 you can 'un convert' your conversion and you will not pay taxes on it.
as an example, say you have $30K in Apple stock .. if on 10/10/2011 the stock is worth $40K (my hope) then you keep it.. but if it goes down to say $20, un convert and you don't pay the taxes on $30
see your tax advisor and you broker to make sure you do this correctly ..