Unless you have a big box phobia check Home Depot or Lowes. We used a Schlage brand. We found in stock 4 sets all keyed the same....there is a number on the box indicating what the key is. They said they would rekey the rest for $5.00 each. We ended up just putting the 4 keyed alike in the regularly used entries. I got a cheap keyless doorhandle for one door, but the batteries went dead pretty quickly and I haven't bothered to replaced them. Doing it over again I would get one that requires no batteries or power.

We got a schlage keyless deadbolt like this http://www.amazon.com/Schlage-BE365VCAM619-Camelot-Keypad-Deadbolt/dp/B000NJJ1MQ/ref=sr_1_3?s=hi&ie=UTF8&qid=1327115690&sr=1-3 it is a little touchy and you might have to reenter a few times, it also turns with a little more pinch effort than I like. It had the best reviews when I selected it. I'm sure you can't get in with anything but the real code. I'd prefer to have found one that is self locking but I couldn't get everything I wanted in one lock. Do a deadbolt is you are worried about security. A credit card can open a regular door lock. I can't really complain but if I had to compare it with my chamberlain keyless garage door opener I'd say that chamberlain is less fussy, and requires no pinching- just push the button, also contractors are familiar with chamberlain and seem a bit afraid to use the newer looking schlage. as far as your oily finger question. we've changed our code several times after certain deliveries, and contractors were done ( or fired) , and changing the code would eliminate an overuse "tell" on any certain keys.

My mother had one on her house for a few years but turned the other way so you had to punch in a code to get out of the house (my father had Alzheimer's and it was a great preventative for wandering.) Most of the one's I've seen have a modern feel to them, the handle on other side had a simple look that was appropriate to the handle. My 80-year old mother didn't have enough of a thumbprint left to use that option, but you can use a key or the code. Her lock might have been a different brand (purchased at Costco.com) but you could leave it in an unlock mode. My sister now has it on her side entry door as she didn't like the look with her very traditional home, but it has solved the problem of lost keys with teen-age boys. Sister says the thumbprint sometimes doesn't work, but since everyone in the family knows the code, it's not a big problem for them. We just used the included handle for the other side, but since I didn't install it, I'm not sure if it's a universal type that you could change if you didn't like what it came with.

We have iron double doors and they ARE heavy. They are very well balanced though and open and close like "butterrrr". My toddler grandchildren have no problem moving them once they are open. Price these doors before you fall in love with either idea. Our door was reasonable (4K +) but they can run much higher. Your hardware for these doors is not inexpensive either, and if you have the requirements that Renovator spoke of for your area of not being able to leave one side latched- a double may not be worth the security hassles. Our double door is inside a security gated courtyard so we often leave it open in nice weather when kiddos are not around.