Streaming Spotify (or other streaming service) simultaneously to multiple rooms.

I've done some research and searching and I think I've found my answer but wanted to confirm.

Here is what I have:

Audio:
Receiver with 7.1 setup in TV/Living room with a HTPC connected wirelessly.
Old set of Logitech Z-5500s in kitchen
Set of powered bookshelf speakers and powered sub for garage
Another receiver with a 5.1 setup in basement

"Receivers":
Airport Express
Two laptops
iPad

Source:
Desktop PC from which to stream from.

I occasionally want to be able to simultaneously stream music to all my speakers. From what I've read, Airplay with Airfoil may be my best bet. I can utilize the laptops, iPad and my HTPC for 3 sets of speakers and I think I'll end up using the airport express as extender to get good coverage to the basement. I'm also thinking of getting the Reemote for Android to control Airfoil from my phone (has anyone tried this?)

Does anyone see any problems with my plan? Seems like a very cheap method to simultaneously stream audio from Spotify around the house.

EDIT: Looks like Reemote is Mac and iPhone only. There are other Android Spotify remotes though. Also looks like you can use iPads as an airplay receiver so I added that to my receiver list. Going to test all this out when I get a chance and post the results.
Edited by tys90 - 12/26/12 at 11:00am

Quick update. Airfoil seems to be the best method...except Spotify is not working properly from my Desktop PC running Windows 7. Every other application streams properly except Spotify, there is no audio output when using Spotify. I e-mailed Rogue Amoeba but have not received a response. Has anyone else had issues using Spotify with Airfoil?

Glad to see someone else was interested in this too.

I ended up buying a first gen airport express to go with my HTPC, the ipad and another airport express.

I had to hardwire the first gen airport express (~$40 on ebay if I remember correctly, much less than a current gen) to a Windows XP computer to get it to update the firmware, I couldn't do it wirelessly or from a Windows 7 computer for some reason.

Once I did that, I had all my devices on the wireless network in the house. I connected my various speakers/receivers then I used a combination of the following:

Spotify running on my desktop computer
Spotimote server running on my desktop computer
Airfoil for Windows on my desktop computer
Airfoil Speakers for windows on my HTPC (acts as an Airplay receiver like the airport expresses do)
Spotimote for my Android

It turns out Airfoil didn't support my sound card but once I switched to the integrated audio on the motherboard, it worked perfectly. Using this setup, I could stream spotify sync'd to all my airplay devices and control the spotify client on my desktop computer via my Android. Spotimote wasn't perfect, I had to restart the Android app a lot but it did the job. Everything else worked great. I ended up buying a license for Airplay so my total cost was $65 or so to get what I needed.