completely of the subject of modes, you could try retuning one of your guitars (and i dont just mean drop D) so when your 'noodling' when you fall into a regular pattern, either it will sound awful (so you'll learn not to do it) or (hopefully) it will sound completely different. and then try different retunings. it might annoy you for a time before you get used to it, but stick with it, at the very least you'll get some new riffs. and then when you go to a standard tune guitar, try getting that same riff. I had to because a friend retuned my only guitar, and shortly after that the battery in my tuner ran out.