I am going to disagree a little bit with folks. (just a little mind you)
Who is telling you that your workouts are too basic? Find out why they feel that way. As a new trainer you don't really have the security of stable client base to tell you that your way is right.
From what I can tell, you need to get results but you must also make it fun for your clients. At least you have to make it enjoyable enough that they want to continue paying you again and again right? If you do the same routine all the time then it might just get boring despite how effective it is. I make up my own routines and I look for variety a little bit in my exercises. You should do the same thing for your clients as it is appropriate. You might decide to do the same exercises even but do them in a circut as opposed to sets. That can be a fun mix up. You may decide one day to do tabata type training with the same good exercises. If you have a fat loss client you may decide one day to take them out for a run just to mix it up a bit.
I think you can add variety without compromising your foundational beliefs about exercising. Roland posted a thread recently from Ross that speaks to this subject matter. Keep it fun and keep it real. In this case, I believe you can have your cake and eat it too.