I'm considering the rental of a wine storage locker at a facility here in Austin (Vault 55 http://www.vault55.com/thevault.htm). I've never stored wine in such a facility before. What questions would be useful to ask to determine whether this place would work? 

Mark, I'm also in Austin and know a couple of people that keep their wines at Vault 55. My wines are at a different offsite facility.

As far as I know Vault 55 is very secure. I heard they use fingerprints for access (?). I might be more worried about the lease default issue so you should ask some questions about that.

In the facility where I keep my wines the prices are different for different size capacity. It is much more utalitarian with no racking or anything so I imagine it is a lot less than Vault 55. Their prices seem pretty high to me but it is a really nice facility. Swank in fact. I also did not want to drive all the way into downtown and then try to park although I understand they have parking there. I go to my storage and quickly grab or drop off wines. Sometimes I pet the pretty bottles (joke) but it's too cold to hang out. :)

Winetex, thanks for the comments.

Mark, I PMd you. Please let me know if you don't receive it as PMs have been quirky.

Here are few questions I learned to ask after I started storing my wine a facility.
1. Is there a consistent window available for pick up or drop. ( the place I store is cheap, but I have to call and confirm the one guy is there)
2. Is there a fee for having wine shipped directly to you locker?
3. Commerce between members for trading or selling unwanted bottles.
4. Are you in control of your locker?
5. Chance tastings or socializing with other members? (occasionally I here about other members getting together to share wine. Those are the best!)
6. Ask if there is a group email list for info related to the storage facility.

Currently my locker cost $50 a month for up to 14 cases. There are cheaper lockers, but I would not have control or the only key. If I have wine shipped there, then it will sit in front of my locker until I get there. The owner uses the space to run another business which no clients need to come to the locker. Late or weekend pickup is not available.
The management of your storage should be able to show you something that protects your wine from Lease default. If not, I would think again about storing my wine there.

Sacramento, CA

A few friends of mine store at Vault 55 and I called them to see how things are going for them using the storage. They said they have had no problems with the facility. matter of fact they said it was the best storage facility they have used. So best of luck to you and I hope that you find out how it will go for you, storing your wine. :)