I many cases most artist show previous commissions and First off commissioned art often follows a repeated pattern as you do it once and the next client wants what they see in the previous painting. In some way no surprises is what most clients want. But also the client that would allow you to paint a large scale painting in which the subject is such a small part of the over all composition such as Sartgent's
Daughters of Edward Darley Boit. Are very rare clients. (this painting is 7ft x 7ft not many clients even have space for a painting that big)
Due to the cost,and size restraints of most peoples houses most of my commissions have been head and shoulder only and most about 18x24in I have done only one full length commissioned portrait as I will not paint a portrait in which the head is smaller then about 4 inches high that is the smallest I will go so if the client is not going to pay (or has the space for) I have to paint what they can afford to compensate me for and still give them what they want. Now I have other paintings
http://homepage.mac.com/mfournier/po.../p1010001.html but that is not the normal commission. I would love to get commissions like Nelson Shanks but that is just not where I am at in my career but the next time my client is the Princess of Wales or the Pope I will surely offer some alternative composition options to the client. I suppose it is the chicken and the egg situation unless you paint large scale alternative compositions the chances of getting a commission to paint one are very slim as people hire you based on what you have painted in the past. But when you are trying to earn a living you don't have time to paint a large scale alternative composition no one is going to buy.