I just did a cake for my mom this weekend and I had never tried the wilton white coloring. I really didn't like it. I don't know if I added too much or what but I found that it changed the texture of my icing.
I have not tried the all shortening icing I am afraid that it will be to greasy tasting or something. I have been useing the Wilton basic buttercream and it works great, what I have found is that if I use the "hispanic" (dominican Vanilla- you can find this in your local spanish store or the hispanic section of the suppermarket) you get a very nice flavor and since it is clear it keeps your icing very white. Caution: A LITTLE GOES A LONG WAY. It is very strong.
P.s. I just found this site a couple of weeks ago and I find myself looking in here every night. It is so addictive. I would love to thank all for sharing reciepes and all the knowledge all of you have and for letting us newbies learn from it all. It is amazing you learn something new everyday on this site.