I can't say enough good things about Synology - their stuff is fanstastic.
For your scenario, absolutely look into the DS212J + Wireless dongle. Whilst I agree that wireless sucks for a NAS, at least synology have one you can buy for it if you are determined to go that route.
With two disks you can have Raid 1 mirrored drives so if one fails, no problem. But even better use the SHR raid type so that over time you can replace the disks with bigger disks one at a time, still have the mirroring but without losing the capacacity of the bigger disk.
Their software is fanstastic, you can access your NAS from anywhere using a browser in an interface that is as simple to use as a desktop. They also have free ios/droid apps so you can access the stuff with the mobile too. A great selection of packages can be installed with a click to provide you with anything from a DHCP server, to a photo gallery, phpmyadmin, squeezebox server, or a wiki.
As you can tell, I am really impressed by them, just upgraded from a DS210J (2 bay 2010 model) to the DS1512+ (5 bay 2012 model) and the upgrade was as simple as taking the drives out the old box and slamming them into the new one (with some extra 2TB disks too )
Plex media server is available for intel chip models like my new 1512+ and I can't imagine there is a better streaming / media centre option in the universe for watching stuff on the ipads and PC's scattered around the house! If you are getting a non-intel model, then there is still normal UPNP/DNLA media streaming too.