Fair point and I'd have to dig into it much, much more to give you a really good answer.  But if I live on a block with a few hundred people with a, generally speaking, narrower street compared to the exurbs where there are a few dozen people at most, then the cost per person for infrastructure needs (roads, water, sewer, communication lines etc.) should be much lower.  However, the infrastructure in my neighborhood is also much more likely to be used by those that don't live there, unlike in the suburbs.  So ironically I'm also supporting those in the suburbs too, to at least some extent.  

Depending on how you look at the sales tax (special districts compared to straight up sales tax) Denver is very competitive to surrounding cities and should arguably raise the sales tax.  

Just to be clear, this is more of a thought experiment than an actual position on the matter.  I don't have enough information at the moment to have a strong opinion on the matter.