I find that I do the same thing - start with photos. Another cool idea that someone shared with me is use an existing layout, and make it your own....scraplifting. It is a great idea - and that way you may find yourself mixing your kits a little more. If you take advantage of the challenges - they will also help you mix your kits. For the most part though I agree with you - I usually stick with one kit. Another trick that I have found help - is that I have seperated folders under my images folder and try to put all girlie kits together, tropical, christmas and so forth - that way going through them is easier too! Good luck - but makesure you are still having fun!
Somewhere in all the madness lies the beauty within