I can't speak to the Denver market since I'm in DFW, and obviously can't speak to the specifics of your building since there are so many varying factors. But I agree with an above poster that $10 psf in tenant improvement seems low, unless you can find a turn-key tenant to occupy that will require very little renovation.
In DFW, for 2nd generation spaces, I've seen LLs underwrite at about $25-35 psf in expected TI allowance (subject to the lease terms and tenant credit rating). If it is a cold dark shell, we would do $60-65 psf. And also, I see many LLs simply offer several months of free rent in lieu of TI if it's a tenant that fits. Also, make sure you account for broker commissions if you choose to use one to lease your building.
Best bit of advice I have, get in touch with a local commercial broker who specializes in that asset class if you haven't already. They will be your best source of information on how to underwrite these deals and what to expect in your market.