If you are at 28% you are in good shape. Me--being in California----few of us go by that rule---and many either get rich or go bust...but we have a greater upside on our prop values in the long run as well as greater possible depreciation in the short run.
Go with a 15 yr mortgage if possible--esp with the rates as they are now. Its nice to see a chunk of principal come off the loan each month. On a 30 yr loan for the first yr--if your loan is say 1500 /mo. you may see 1440 interest and 60 principal. a bit disheartening. Whereas on a 15 year it'll start out at 900 interest and 600 principal and improve quickly from there.