I know you have a tripod, but it is nice sometimes not to have to use it for low light situations. I couldn't imagine being w/o my 35/1.4L nor my Zeiss 21/2.8. I use B+W MRC UV filters for all lenses, and for landscapes often a circ pol. You say you don't often do portraits, but I love my Zeiss 100/2.0 for portraits (and macro) -- give the Canon macro to your wife. Good luck, and have fun!
I've had (or have) the 24--105, 35/1.4, 85/1.2, and 135/2 for the 5DII. My favorite of the Canons is the 35/1.4 for versatility, sharpness, and low light capabilities, followed by the 135/2 for sharpness, fast AF, and ease of use.
My favorite lens is the Zeiss 100/2.0 macro, followed by the 21/2.8.
Get the 135/2.0 now: fast AF, great bokeh, sharp. Then save your pennies for the Zeiss 100/2.0 macro: one stop faster than the Canon 100, and sharper, better bokeh, no distortion, great for portraits and macro.
I don't have a 50 or the 24, but do have the Zeiss 21 and 100, as well as the Canon L 35, 85, and 135. I end up using the 21 (mostly landscapes, some people/street), 35, and 100 most. I agree the 35 is much more versatile w less distortion. Tough call about waiting for next gen. Zeiss also has a 35/1.4 but of course it is not AF. Don't forget EgS focusing screen.