In comparison to your 35mm and 50mm primes any zoom with this much range will most probably be a big disappointment for you and complete waste of time and money (I also fell into that trap with a crappy 35-135 Kiron everyone recommended and accordingly feel hard about these lenses). If it doesn't, it is a sign that there is room for improvement for your technique or you could as well use a simple p&s instead of a demanding SLR. I'd keep looking for a nice 200/4 and then something to fill the gap or a (more expensive) 80-200/4.

best

Stefan