I'm working on a pullover that has seed stitch on the edges and some cables interspersed among stockinette.( http://www.knitpicks.com/Projects/Projects_Display_Yarn.aspx?itemid=30695220&yarnid=5420141 )What stitch do I use to knit the swatch? I first did it in seed stitch, started working on the project and then ended up frogging the whole thing because I was getting ribbing where I should have had seed. (a whole other problem) Then when I started over I was practicing my continental knitting which I guess could have effected my gauge. When I measured the bottom band I'm off by about 4 inches. So I guess I need to try another gauge swatch.
Usually the pattern will specify a pattern for the gauge swatch. If it truly doesn't (look closely!) then you should use stockinette.