I have the Westminster PM and it's a nice shoulder bag. It's pretty comfortable on me and is lightweight. The only thing is the handle drop needs to be a bit longer (about an inch or two). I don't have the Trevi PM but heard that it's a bit heavy. I'm not sure about the Saleya MM.
Thanks so much for your replies!!! I bought the Westminster GM recently and was considering whether to sell it and use the $$ to purchase Trevi PM or Saleya.. Now I think I will keep the Westminster and save up for a Trevi PM or Saleya next. I have 2 questions at this point: (1) Is the Saleya MM bigger than the Westminster GM? (2) What sorts of bag charms go with the Westminster? ThNks heaps!!! Love to hear what you think... Might wanna get a bag charm soon to dress up the Westminster. I'm 5'2".
Yay!! Keep the Westminster...............I have the GM also and I am getting ready to purchase the red heart charm. It is just so cute........I tried it on with my westie and my speedy B and it looked great on both.
Yeah I'm so glad we have this forum, I have like-minded friends to discuss purses with!! Yes will definitely keep the Westie. I just came home from shopping and saw someone carrying the Saleya MM. Now that I finally see it IRL, I think the Westie's base doesn't stick out as much as the Saleya MM hence looks nicer as a shoulder bag, and the pleats on the Westie are so pretty. Yes I was thinking of a bag charm with some colour like a red, as it goes well with the bag and matches the interior too. Please post some modeling pics of the red bag charm on your Westie!! 
Yes the Galleria is very pretty. I have however recently started falling in love with Damier Ebene as it's a classy and practical choice.  Never thought the day would come when I would start falling in love with Damier ebene as all my other bags are in Mono Canvas. In fact, Westminster GM is my very first Damier ebene purchase ever! I agree Galleria is such a lovely choice. Does it come in ebene though?