I told myself I wasn't going to get into these discussions again, but wth.
But all I'll say is you're not sharing enough for anyone to be in a position to offer the best advice. Example, you're not sharing what kind of weights/machines you're using, nor how much weight you're lifting in the various exercises. If you're only lifting 5 lb dumbells and 20 lbs on a bench, then of course it wouldn't be very reasonable to expect much muscle gain. Then of course, there's the approach itself. Heavy weights and fewer reps are going to typically yield more mass quicker than light weights and 10-15 reps. Some people want bulk, some want definition, some just want strength. Personally, the latter better defines my goal these days.
IMHO, I would not give up running, unless you're going to substitute it with walking outside, treadmill, etc. Running should have very little effect on muscle loss, if any, and assuming you have a decent diet. I'm also not a big fan of all the nutrition drinks and all the supplements going around, but again, an individual thing. And I suppose I can accept it doesn't hurt. Myself, I eat whatever I want.
To a certain degree, it's all going to vary by individual. We don't all gain/lose the same way, and no one program will be best for everybody. Honestly, I'm not really interested in muscle definition or having a washboard stomach or any of that anymore. Been there, done that. But now my schedule is very casual. I still lift some weights 3-4 times a week, and I walk for 30-50 mins almost every day on a treadmill or outside (rods and screws in the back now so running is out of the question). I have sets of 15/20/25/35 dumbells, and for example, one day I might do 3 sets of 10 curls using the 35's and the next time I workout I might do 4 sets of 15 with the 25's. I use the dumbells for 3-4 different exercises and vary the workout a little each time. I recently got on a bench at the gym and pushed 3 sets x 10 reps at 225 lbs. Not what I could do when I was 20 or 30, but at 54 I don't think it's too bad, and it's more than adequate for what I'm after. I'm still staying in reasonably good shape but not killing myself or burning out in the process.