sb wrote:
But that is sooo hard when you are taking photos of birds in the swamp or players at a game!
Original poster is looking for a lens to use at weddings and other family events for portraits... not birds in the swamp or players at a game!
You aren't going to find a single lens that does all you want particularly well. The whole point of an SLR like the 70D is the ability to change lenses to adapt the camera for use in different situations (otherwise, if you don't want to change lenses, just get a Powershot G1X or G3X).
For portraits, zooming with one's feet makes a lot of sense and an 18-135mm covers the most ideal portrait focal lengths. My most used portrait lenses (on crop camera like the 70D) are 24-70/2.8, 28-135, 50mm and 85mm.
But if you want more reach for other purposes, a 70-300 IS USM (around $600) would complement the shorter lens nicely, without being too big, heavy or expensive. As an f3.5-5.6 lens, a 70-300 would be mostly a daylight lens. For indoor/lowlight work, a 70-200mm f2.8 IS USM II would be a better choice for it's larger aperture, but doesn't have as much reach and costs upwards of $2000 and is bigger/heavier. Tamron 70-200/2.8 VC USD is getting a good reputation, too... sells for about $1500.
(EF 75-300 non-IS, non-USM can be found a lot cheaper, but is not one of Canon's better lenses and is best avoided.)
If you shoot a lot of portraits, I'd recommend EF 50/1.4 and EF 85/1.8 as two reasonably affordable and even more ideal portrait lenses. With their large apertures you can shoot low light and/or can blur down backgrounds nicely. They also are relatively small and less intimidating or intrusive than many of the zooms. These lenses sell for approx. $400 each (including lens hoods... be sure to get those, which are sold separately, especially for the 50mm... It's needed to protect that lens, tho I'd recommend one for any lens, anytime).
For occasional macro/close-up shots at higher magnifications than the lenses can do on their own, simply get a set of Kenko Macro Extension Tubes ($124) and learn to use them with the lenses you've already got. The current "CA/AFs" version will work well on either the 18-135 or 70-200/70-300 or 50mm or 85mm. In fact, they can increase the magnification of any lens, usually with very little negative effect on image quality (there is some vignetting on the 50/1.4 at it's largest apertures).
For portraiture in particular, you also might consider getting a flash, an off-camera shoe cord and a flash bracket.