I've done a quick search and couldn't find anything about this, so:
Is there any reason I would use one over the other? Given they're both wireless signals, which one eats up more power? Any advantages for using one vs the other one?

well one is that a lot of computer dont have bluetooth built in..

Well yeah, if you're comparing the two, the assumption is that you have a fully compatible computer...

taken from wikipedia:

IDK what revision of the bluetooth protocol our droids have but I would imagine WiFi would have a larger throughput rate.

The only thing i can think of is the connection speed It looks like what it comes down to is the bandwidth of the connection.
What is the maximum transfer speeds you guys have seen over BT? Wifi ad hoc should be connected at 11mbps with wireless b; given real life conditions probably 5-6mbps. While transferring a file over BT, I cap out at 200kb > 1.6mbps. You guys see similar results to that?

Any other things i might be missing for bt vs wifi?

The max realworld throughput for BT is like 780kbps. I think Syan is close and 1.6mbps might be the max, but because of data going both ways, the realworld results is lower - I remember something about 780kbps. Of course there is the supposed BT upgrades/revisions, like EDR (which is like 3 or 4 mbps max? Though I don't know if that is an actual BT revision that is coming or here or planned or scrapped or whatever).

BT is a weak radio by design to associate with immediate peripherals. WiFi is designed for house/floor size networks.

BT is designed for short small transactions. WiFi is designed for large data transfers.

BT has its best implementation in the most frequently used protocols (e.g. printing) not so good in headsets, and usually not at all optimized for Dial-Up Networking (DUN). WiFi is designed for data transfer

BT software is designed for peripherals, and the code-association and related software is more complex. WiFi can be set up with no authentication, or simple passphrase or hexadecimal key authentication. In either case WiFi associations are easier [at least under Linux].

Finally, they use the same frequencies. This means if WiFi is active and BT is active they will interfere with each other. In the presence of existing WiFi, I personally avoid using BT.

IMHO, YMMV, Go Lewis.

E

"In the presence of existing WiFi .... "

But you pretty much just described the country.

And joking aside, good summation.