If your your budget allows and you are tossing up the idea of having seats at your wedding ceremony, do it!
Let’s start with the obvious, chairs inadvertently forge a proper aisle and create a bit of order for the arrival of the bridal party. And don’t underestimate the fact that your guests will want to settle in with a good view. Providing a place for them should make everyone’s experience at the ceremony more enjoyable. People can relax a little bit more and they can really take it all in.
If budget is an issue then you should consider hiring or borrowing a few chairs as you don’t want to leave any oldies or pregnant women in a pickle. Imagine how tricky it might be for them to stand for an hour. Doing it this way means the remaining guests can stand behind the chairs. A seasoned pro of a celebrant or photographer will always divvy the guests up prior to the ceremony commencing so your photos look balanced.
Other things to consider is what the weather might be like on the day of your wedding. If it’s going to be a very hot day then expecting your guests to stand for 30 - 40 minutes might be uncomfortable. And if you're getting married in a garden your high heeled friends might start sinking.
So, a general rule of thumb, if you can afford seats - do it!