On the tables
If you are considering any kind of arrangements to put on the head table, think about what pictures will be taken there. If the very complex arrangements to your it will not be distracting in the photo, then you may want to reconsider your plans. Again, the florist can help you out with this kind of logistical problems, especially if they were local. Many already have experience in any reception hall, so they know what they have to do.
The guest, in spite of the large flowers can look great in the reception area, you should consider that it would be to sit at one point. The presence of the largest floral arrangements and block their view from the other side of the table or the dance floor or head table is not very well prepared.
Think about where your guests will sit and what they will be able to see. They may have cameras to take pictures of themselves brought, so you do not want to block their view.
Ideas that you can use
On the other hand, you can also choose flowers that are less to the table. Some couples like to choose a set of floating flowers and candles to add a bit of warmth to a table. And they also serve as conversation pieces as well.
Floral arrangements do not have to come from bridal magazines or shows in order to be useful in your wedding. Look around and see what are the types of arrangements can be done. Talk to florists about what you need and see what they suggest.