Jackets vs no jackets

I'm of the opinion that the level of formality should be the same for everyone in the wedding party. Are you wearing a formal dress? Are the bridesmaids wearing formal dresses? If your FI wears a jacket, the groomsmen should wear a jacket. Men who accompany women who are dressed up, should be dressed up.

This whole vest fad will soon come to an end. Your pictures will definitely look dated, but then again most wedding pictures do. Vests are meant to be worn under a jacket, especially the kind with only a lining fabric on the back. That type of vest is not meant to be worn alone (except as you mention later in the evening after the men have removed their jackets).

Why not dress them in something appropriate to the climate where you live? Linen jackets or suits are perfect for warm weather.

We plan on doing this as well. FH wanted his guys to be comfortable since its a summer wedding and the ceremony is outside and we think it really fits with the laid back summery feel of our wedding. Our girls will be in knee length dresses so I think it all fits! I definitely think this a classy look and its trendy right now without being something you will look back on in 20 years and wonder what you were thinking.

We're doing the same. FH will most likely take his jacket off after the ceremony, and knowing our groomsmen we just decided to not even bother getting jackets they're going to feel uncomfortably hot in.

Considering how hot it's going to be, I would skip the jackets for everyone. That sounds miserable, honestly, and I feel like all the guys will be sweaty in your pictures.