Warby Parker is a class act. You can go to their website, pick out five glasses frames you think you might like, and they will send you a sample of those for you to try on free of charge.
They include a label so you can send them back at their expense.
Warby Parker is very tempting. Alas, I have a big head, so even their largest sizes will not fit me. I will have to go to an eyeglass shop as usual and have them bend the frames around to fit my head.