I love Elbow. Apart from the obvious things (Peter Gabriel, David Sylvian, Blue Nile, Talk Talk etc) ,I'd recommend;
Mercury Rev (Especially the last 2 albums)
No-man (Especially 'Returning Jesus' and 'Together we're stranger')
Tim Bowness (My Hotel year)
Henry Fool (perhaps more overtly prog?)
(I have to admit a connection with the last couple of albums - I'm on them! But hey - I feel they're great albums I'd buy if I wasn't
)
Sigur Ros
Godspeed you black emperor (more overtly 'prog', I guess).
I feel that later XTC might float your boat?
You may also like Muse, Tool and The Mars Volta - though they don't do anything for me.
Regards
Stephen