1. The Albini White Oxford Chambray fabric since it could be dressed up or dressed down. If you want something cheaper and more durable than the Heavy White Oxford but that might feel thick in the summer as well look more on the casual end of the spectrum. http://propercloth.com/fabrics/white/casual/
I'd get soft two button cuffs since most gents I see wear one button so it's a subtle "dash" of style, soft placket, and either the Soft President Spread collar to play it safe or the Soft Roma Cutaway collar if you want something a little more big and bold. It's my favorite collar for how it looks with a tie and without a tie and how it tucks under a blazer.
Do you use the supplied collar stays with the Soft Roma shirts? I never use them, but my Soft Roma collar points tend to 'fly away' without the stays, worn sans tie. Which is a shame, because it just doesn't make sense to me to wear a soft collar'd shirt with metal stays...
Any trick to keep the points tucked under the jacket?