Likely, your initial thought when choosing who to celebrate your marriage with is to include everyone who has ever meant anything to you in your life. Then reality sets in, you realize your fiancé has a guest list as well and that, as the number goes up, so do your expenses, forcing you to reallocate your budget.
There are many reasons for selecting a venue among those being a place with sentimental value, somewhere you just happened upon and had a feeling about or a location which may not be your first choice but will accommodate the numbers of guests you have invited.
While every person you do invite most likely hopes to attend, not everyone will be able to. Some may immediately let you know via your RSVP cards but others cannot predict unforeseen circumstances and cannot inform you until much closer to the date.
One thing to consider is the number of guests coming from out-of-town. If they are family or very close to you, the likeliness of attendance is much higher than if they are friends from college for example. Typically, when averaging the two, approximately 55% of those coming from different locations will actually be present.
Local invitees are much more prone to commemorate your day with you so expect relatively 90% of those to attend. However, something may occur which keeps them from attending as well.
Therefore, your site should be chosen not by the capacity it is able to accommodate according to the number of invitations you send out (given it is not significantly less) but rather by what feels right and seems to be the ideal location. After all, if your heart is set on one particular place, modifications can always be made so as to execute what you’ve dreamed of.