I've been to the BLU and the Park Inn in ZRH a few times. Whilst the premium for the BLU as only within-aiport hotel is considerable, for my purposes it is usually worth the price.

Staying at Zurich is usually quite expensive at any hotel, yet as a statusmember with CC the BLU often enough wins for me in terms of value for money.

Some additional thoughts:
- The shuttle to the PI is not that comofortable and not always available.
- Reception at the PI is often enough staffed with only one person, so even if there's a only a few people coming with shuttle, try to jump out first of the van to be ahead of the queue
- the BLU has some decent train connections from within the airport, whereas the PI is in a commercial area without any connection by bus etc. to the city I remember
- Breakfast at he BLU is usually quite relaxed, whereas in the PI it sometimes gets a bit hectic with some smaller groups of travellers to (?) Asia buzzing around the buffet