What to buy next?

So I've come to the cross roads where I need to decide what item I'm going to buy next. My current setup includes the following:

7D
430 EXII Flash
Canon 70-200 2.8 (Non IS)
18-55mm IS
Nifty Fifty

We are expecting our first child at the beginning of April (Woohoo!!!), and I'm look to expand the kit with something that will benefit more portrait/candid style pictures. (Probably targeting to eliminate the 18-55 if I get a lens and use the new lens as my primary portrait/walk around lens with nifty fifty in tow as well). I have about $600-$800 to spend (although I could stretch more if I wanted to). I think my options are as follows:

- Add another flash (Canon 600EX), ~$450 new (Mainly for portrait style shooting, using the 600 to control the 400 off camera)
- Tamron AF 28-75mm F/2.8 SP XR Di LD Aspherical (IF), ~$450 new
- Tamron SP 24-70 DI VC, ~$1200 new
- Canon 17-55mm F/2.8 IS USM, ~$850 new

What are everyone's thoughts about these options? I'm personally leaning towards a lens (as the 2nd flash would be solely for portrait type stuff). What are everyone's thoughts advice? Of the 3 lenses above, which offers the best bang for the buck? I've never used a Tamron lens but I have heard good things about the VC model (and bad as well), is it worth the upgrade over the LD model? What about the canon 18-55mm 2.8? I've not really seen too many people using this lens on the forum, and don't know if its because its marginal and people either go with the Tamron's or save for the Canon 20-70mm F2.8L. I shoot a lot of sports/out door stuff with the 70-200, would either the cheaper Tamron or the Canon be fast enough to be used as a complimentary shorter focal length to the 70-200 in these situations? I personally would like to go best bang for the buck (out of this group may be the Tamron 24-70mm VC), but also don't want to over spend as well. Thoughts?

To start with when baby is young and not moving much you'll be fine with your 50.

As they get older they start to zip about the place. Indoors, where your 50 is too long on a crop body and there isn't enough light to use a zoom this can get really problematic from an ISO standpoint.

Personally I love fast primes.... It's not on your list, but a what about the Sigma 35mm or 30mm Art (depending if you want move to FF one day)? Either would make a nice indoor general use / portrait lens. It'd be within your budget more or less.

If you're keen on getting a zoom then disregard, but thought i'd throw it out there as another option. I'm sure plenty of others can comment on the zoom options, though you might want to post the question in the lens forum rather than the kids and family one.

I haven't hit the zipping around stage with my kids yet, but I got the 17-55 2.8 Canon and love it so far.

Anohter thoguht -- just wait and see how your photography grows along side baby and let your needs drive your purchases. There's a very big FL difference in the wide end between the 17mm canon and 28mm tramron. Seems like exactly the situations you'll be using it in would be the main driver here and you may not know that yet.

Congrats on the new addition to your family

I find the 28-75 on a crop body too long for everyday use. When I visit the grandkids, I most often use a 17-55mm and a 85mm. However, if I had one, I would probably use a 30mm f1.4 because of the speed. I much prefer shooting candids of the kids, and faster is better so I can avoid using a flash.
Your 70-200 will be very useful in a year or so when your child becomes mobile and likes being outside.
Be prepared to shoot more than you ever have

I would recommend either the 24-70 or a prime like the 30. I shoot my kids mainly, and a lot indoor. I get by most of the time with my 50 and 30, although I often wish I had a good 2.8 zoom too. A lot of people recommend the 17-55 on a crop, but for photos of kids, if thats your main thing, I find the 17 too wide and probably the 24-70 just right.

I'm using flash more and more myself and find the 430 limited in its rotation. The 600 is the newest but I'd consider a used 580 II for about $300