I'd say get a 24-105 to replace your stock lens and use as a medium tele. You could leave it on 24/7, and eventually add a wide angle or longer tele as needed. 38.4-168 (equivalent) at f4 with IS is pretty good,and you should be able to shoot most things with that. Keep the canon lens until you can afford a 24/28 equivalent if you need it (that length is good for traveling/indoors or anywhere you can't take a step back/group photos).