Weekend backpack for Washington DC

It's weird because I said to myself a while back that I would never start one of these threads because I know how personal choosing a bag is, and yet.... here I am.

I currently have a Slingshot 300 that I have used on multiple trips but I just don't think I want to deal with it any more; the one shoulder really starts to hurt. I'm thinking I still want to keep with a backpack but I'm not sure. I'm thinking a shoulder bag (messenger bag) would basically be the same thing with all the weight on one shoulder.

What I'm looking to carry is:
5D2 (can be gripped but looking to loose weight)
24-105
17-40
70-200
50 1.4
Misc stuff

I don't really have a budget but am I'm not really liking the idea of forking over $200 or something like that. What do you guys/gals think? What will give me easy access (without taking the bag off) yet still provide me with comfort throughout the day. The one bag that I've already seen is the Lowepro Fastpack.... anything else?

At $60, this will fit your budget and gear and still leave room for incidentals and a laptop: http://www.adorama.com​/KADR465.html

I use it and like it.

Edit: Actually, this is the one with the laptop pocket, but its a bit more expensive at $90: http://www.adorama.com​/KADR467IBK.html

That looks like a possibility but I'm just wondering how easy it would be to get to the gear without taking the bag off. Has anyone used a sling bag with my amount of gear for more than a day or two. Would you recommend one? I saw a lot of posts while researching about people getting waist packs; aren't those big and bulky on the waist?

Cougar548 wrote in post #9899034
That looks like a possibility but I'm just wondering how easy it would be to get to the gear without taking the bag off. Has anyone used a sling bag with my amount of gear for more than a day or two. Would you recommend one? I saw a lot of posts while researching about people getting waist packs; aren't those big and bulky on the waist?

I can get into this bag without taking it off. I just take off one strap and swing it around to the side, much like my Slingshot 200. It is not a problem.

What about backpack size? I just noticed on the Capital website that bags larger than 13"Wx14"Hx4"D are prohibited... That pretty much takes out any backpack and most shoulder bags. 4" deep is pretty thin and I'm sure you could get by with something a little bit bigger... Anyone have advise on limitations within the buildings?

Not really any limitations on (reasonable; don't try to bring in a rolling suitcase) bags at the various Smithsonian museums (I'll loosely include the National Gallery of Art in this, although it's separate) although they say "No Tripods". They will want to visually check your bag for knives, etc., though.

PM on its way.

Smithsonian Security Policies
Most of the museums, whether they allow photography or not, have lockers or checkrooms where you can leave things.