I try to follow a workout routine were I start off with 80 to 90 minutes of cardiovascular exercise like spinning, cross-trainer and or stepper. This is followed by weights for an hour involving all the upper body muscle groups. I am trying to loose weight and tone up at the same time but not put on any muscle bulk. How can i change my routine as I think I might have plateaued and am experiencing no weight loss on the scales. Is doing the weights first followed by the CV workout a good approach? Any and all advice is welcome.

Our bodies do get used to a workout routine. Even if we try to switch it up each day, our body can get used to the pattern that we work out in.
What I would recommend is to try just one form of cardio for a month and one type of weight lifting. Then, switch every 1 to 2 months.
Here's an Example:
Jan/Feb: Spinning and Free Weights
Mar/Apr: Cross Training and Pulley System Weight Lifting
May/Jun: Stair Stepper and Weight Machines
Jul/Aug: Spinning and Free Weights
Sep/Oct: Cross Training and Pulley System Weight Lifting
Nov/Dec: Stair Stepper and Weight Machines
That way, every two months you switch it up. You keep your muscles guessing. By doing the different weight lifting systems (free weights, pulley weights, and machines) you'll be using SLIGHTLY different muscles and get a slightly different workout.
Don't switch up every day or week. Wait at least 4 weeks before you switch routines. (of course it's ok to throw in a day or two of something else here and there, but it's really recommended that you stick to one thing for one to two months).
Also, rest for a day inbetween your weight lifting. Only lift 3 or 4 days a week. Your muscles need that day to repair the microscopic tears in the muscle.
And, (as I believe everyone already knows) if you want to build muscle mass, lift the maximum weight possibe while still being safe and do as many reps as you can (if you can do more than 20, it's not your maximum weight). And, if you just want to have lean, toned muscles, lift less weight, and do more reps.
Another way to maximize your workout is to do the motions SLOW and CONTROLLED. Focus on the resistance on the way down, as well as on the way up. Each move should usually take about 2 seconds each direction (slowly say to yourself, "up, two, down, two, up, two, down, two...").