Tamron 18-270mm f/3.5-6.3 Di II VC PZD AF Lens for Canon + Canon 50mm F/1.8 Bundle Deal $464 + free shipping

Quote from -Oz- : From a pure tack sharp quality no. From a convinience standpoint yes. The ability to go from shooting close to far is pretty nice. This is what I would consider a good walk around lens. I current have a Canon 18-200 and the 50 plus the 18-55 (got rid of the 55-250) and most of the time I leave the 18-200 on there so I get the shot. If I have time to plan I'll switch lens. Now with that said, this is obviously not an L lens and you will get some distortion at certain points. I use lightroom and it handles all of that distortion. bottom line: If you are looking to expand from those two kit lens this could be a good start; especially because you can sell your 55-250 on ebay for ~$100+.

I actually own the 18-270, both the PZD and non-PZD versions. Neither are sharper than, say, the Tamron 17-50 f/2.8, the Tamron 28-75 f/2.8, or the 50mm f/1.4, all of which I've owned. However, it makes a great all-in-one lens for times when you're travelling or otherwise do not want to bring multiple lenses with you. This lens cover the entire focal length - from wide to superzoom. If you're a professional shooter, this lens will not suffice. However, if photography is more of a hobby, the lens will suffice. Also, this lens is quite compact and light, especially compared to the non-PZD version. Of course, this lens has its issues, but it's a lens for convenience rather than a lens for when you need absolutely tack sharp photos. The reviews initially also scared me; however, for an amateur hobbyist, I realized that the drawbacks of the lens was far outweighed by its conveniences.

Some people argue that the 18-55 and 55-250 combo offers sharper lens, and that may certainly be true. However, I took the 18-270 on a vacation and I loved that I only brought the 1 lens with me.

As for the 50mm f/1.8, I also owned one but ended up selling it and replacing it with the 50mm f/1.4. The nifty-fifty is a great lens, especially at that price. As the folks here have said, you can easily flip that lens on Craigslist for $75-$100. $100 seems like an insane amount, but I actually sold my nifty fifty for that price a few months ago (granted mine came w/ a B+W UV filter).