We've been buying weekly flowers as part of the Spring Cure. We almost never use a regular vase for flowers, preferring to mix it up with containers we find around the kitchen. Our favorite vase is a simple drinking glass. Our other old standby is a yellow pitcher which we arrange using good old Scotch tape as a guide...
This is a photo we took of our flower-arranging process during the Fall Cure. It works for a number of vessels, including broad vases and bowls. There are a bunch of other household items you can use to hold flowers including tea tins, cups, and bowls. For more ideas, see this post.
The Scotch Tape flower-arranging technique:
1) Fill the vase 3/4 full with water.
2) Tape a grid across the top of the vase.
3) Cut the stems of the flowers on a diagonal.
4) Cut them at varying heights that measure 4-6 inches above the top of the vase.
5) Pull off any leaves towards the bottoms of the stems (these will rot and pollute your water).
6) Start arranging the middle of the vase, working outward.
7) The flowers will "stand" in their spot, making the arrangement look fuller.
8) Fill out the vase, cutting stems and rearranging as you go.