Hi Hepburn, am not on here much but liked reading this thread as I was thinking much the same as you re bright colours when expecting my first. I really loved some of the H&M stuff, they do v cute rompers for the summer which are basically short-sleeved knee-length all-in-ones. More "outfitty" than a babygro, and I think they looked nicer than vest & trousers, cos babies don't exactly have waists so you get giant belly overhang (or was that just my podgy boy...). Gap also had nice things like this, and I loved the toby tiger though could never bring myself to spend quite that much once I'd found the H&M ones (I did find their winter stuff to be less exciting though). Other shops to try are Du Pareil Au Meme, and Polarn o Pyret which is hideously expensive but gorgeous. Pumpkin Patch were also good. But I also had a couple of M&S multipacks of "newborn" and "0-3 months" and kept the receipts so we could take them back if they weren't needed.
Also still worth getting a couple of multipacks of white / cream stuff in case all the other stuff gets pooed on and you run out of things to wear! Can get through quite a few changes in one day, despite them growing out of it all in the space of a few weeks. You can always take it back if you never use it.