Mama,  I think you need to go to a running store that will watch you run and recommend shoe, then you can try it on and see how it feels.  The incorrect shoe can lead to issues. Hard for anyone on the boards to give you your needs with shoes.  

I have worn the Inspires and never thought of them as that heavy.  But your perception is what counts.  I could recommend shoes that work for me but they might be terrible for you.  My current shoes, heavy to light, are Asics DS Trainer, Mizuno Wave Precision, Saucony Mirage, Saucony Kinvara 2.

Take a look at the latest Runners World shoe reviews(March, 2013, I think) to get some ideas of shoes that meet your needs (some stability, enough support for a marathon, relatively light weight).  Then head to your friendly running store (NOT a "big box" store like Dicks) to try on as many as you can. Run around the store in each, or on a treadmill if they have one (some will even let you run a little outside).  Pick the one you think will work the best and feels good.  Personally I find that what feels best usually works best.  Remember that you'll be running 26 miles in them.  Do at least one run over 12 miles in them before the marathon.

Len