You mention that by Series A, companies want to customize. Is it more a function of wanting some of their own common space or a desire for individual expression?
At least in silicon valley, the annoyances still exist but don't rise to the level of huge opportunity to fix, since the current solutions solve them pretty well, and the pain-per-customer is finite (you only really set up payroll once, etc.)
It's just annoying. The real pain points remain 1) finding great people and hiring them 2) managing teams 3) product 4) customers 5) funding. Office space is the only minor issue which ever rises to the point of serious, and it's only exceptionally bad if you're looking in Palo Alto (SF and even MV are fairly ok). Admin overhead isn't on the list.
(unless you really want to solve it, but there are a lot of reasons why startups aren't great customers. Only really in the Bay Area and maybe NYC is there high enough density to come up with something, and since most of this is regulated per-state (and per-city in NYC and SF), you'd probably want it to be locally focused.)