Hi Candace,
I've been reading YLF for about 2 years or so. I'm 53, 5'4", size 8 on top and a 6 on the bottom. After reading your post I felt compelled to respond, eventhough i have never done so before. Because of my small frame, age and personal preference I dress very tailored. I stay away from large prints, frilly, and flowery patterns. I like classic clothing in good quality natural fabrics. I too, like you am not a pastely person. I prefer crisp white cotton blouses with a neutral pant and cardigan. Keeping my hair short, and highlighted, I feel very polished, not at all dowdy.
In the past I have attended high school sorority events with my daughters. By all means if you feel comfortable in a flower print dress or skirt go for it. I have worn white capri length pants with a sweater set and a simple flat, feminine sandal. A colorful, (not loud, or beach wear) skirt works well too. Lily Pulitzer is a look you may see at a sorority tea. A simple tailored linen dress would work as well which can be topped with a cardigan.
Lately I have been thinking about what to wear to my son's May graduation from an Ivy League school. For me the look will be uncomplicated, simple yet sophisticated. Possibly a small black and white geometric print A-line shirt with a white tank and finely knit black cardigan, I shop at Talbots (be careful not to look matronly), and Norstrom. Be true to yourself. Good luck!