Don't stay in them myself as we live too close to BHX - but there IS a Crown Plaza Hotel in the NEC complex adjacent the airport that you might want to check out.
I personally wouldn't encourage anyone to rush to the Holiday Inn on the A45 (by the Cargo Terminal / Old Terminal Buildings) or the Metropole (also at the NEC) which has nice facilities (health club etc) but it is HUGE and very expensive - catering largely to the conference trade.
The New Premier Travel Lodge (again on the far side of the NEC) has only been open a couple of years, will be basic, but should be clean and comfortable to tide you over for one night. The Novotel is literally across a service road to the Main Terminal (no more than 100m ) - it's clean and functional but soul-ess - again OK for a short stay.
If you want to look a little further afield for a bit more charm, you could try the Manor Hotel in Meriden
http://www.manorhotelmeriden.co.uk/index.php - I believe they do offer holiday parking, but please double-check!! Meriden used to be known as "The Centre of England" (hence it's name) until some erosion and silt changed the shape of the UK. It has a couple of hotels (Bulls Head, nice food, rooms over a popular pub/restaurant - and Strawberry Bank, plus the Manor - popular locally for Weddings and the like), a few shops on the "village" green, where there is the Cyclists Memorial, and even a duckpond!! It's about 5 miles from the airport, but you'd never guess as it still has it's rural feel. You could also check out the Forest of Arden Hotel (Marriott) at Maxstoke just north of Meriden. Has 2 fine golf courses, leisure club, fishing lakes and is set in a deer park!!! Absolutely beautiful location - but I'm not sure what the situation is re parking and it's unlikely to be cheap!!!!
http://marriott.co.uk/Channels/globalSites/propertypage/UK/cvtgs