Hi Dean,
to IIS.
These two beasties, though both reflectors, they offer very different things.
The Celestron is a computer controlled scope, requireing at least two stars to align every time you set up. Though convenient to some who don't know their way around the sky, it does, to me, take away a part of the astro feeling of not really familiarising yourself with the sky.
The 10" dob is a bigger "light bucket", where you will be able to not only see fainter objects, but accessory wise has much more available to it, like the ability to use 2" eyepieces, which can be much more comfortable to use.
Niether scope is suited to long exposure photography as you really need an equatorial mount to track along one axis (the Nexstar works in two axis and the image will rotate in the photo frame). However, you can do plenty of Lunar & planetary photography, and with quite inexpensive gear too. There are several articles in the Projects & Aritcles heading in the top right margin on this, including one on making your own astro-cam from a webcam.
I wouldn't think either would be suited to a small balcony. The tripod of the Nexstar would get in the way, the 10" dob has a big 'turning circle', and their respective focusers will inevitably find itself in an awkward, if not inaccessible position.
They are also very different animals to carry and it is something to consider if your wife, or you, might struggle with handleing.
I'd suggest two things before puchasing either one, and the surprise is still there if that is the original intension:
1- Take her to a star party to see what these and other scopes look like, perform, handle as ease of use and set-up/take-down.
2- take her to a good astro retailer and have her take her time in ultimately deciding.
There are many astro clubs that hold regular get togethers and the Star Parties forum lists many other get togethers too, and there are several REAL astro retailers that can help, not department stores.
It is not just size that matters, but a good scope is also one that gets used, not stored because it winds up being too awkard/complicated to handle.
Mental.