Long Hair Prom Do!!!

Hey, I''m a high school senior starting WAY early on prom (it''s in May), and I need to nail down an at-home-friendly do. My dress is backless, with very thin straps over the shoulder, and is turquoise, beaded all over (seriously, it weighs like 5 pounds). The hard thing for me is that my hair is very thick, very heavy, almost waist-length, with a wave--almost a loose curl. I''ve been working with a sleek updo, but those are really hard to get to stay up. I need help with doing a simple, not too "big" updo to fit my round face. Help me somebody!!!

~~i don''t mind cutting bangs in the front... i''m almost definitely planning on doing some kind of an updo with a low part in the front at least, then cutting and pinning back long bangs (it''s not the first time i''ve done it)~~