Best lens to use for a concert?

To be more specific, I may or may not be going to a concert on 4/20, Rihanna to be exact. IF I do get to go, of course I wanna get some solid pictures using my Nikon D3100. I only have 2 lens to my name, the widely used 18-55mm and the 55-200mm. My main question is if I sit in the nosebleeds (which I kinda don't want to but hypothetically) and use the 55-200mm, will I still be able to get good pictures? Also, if hypothetically I were to sit near the back in the floor area of the venue, will I still get good pictures with either lens?

Unless you have a venue media pass, I doubt you will be able to take a fully adjustable camera like your fine D3100 into the concert.

Look at your ticket for the restrictions on cameras, video cameras and audio recorders.

The further a way from the stage, the longer lens you need.

Concerts like that genrally do not allow "Professional cameras." ( Cameras with detachable lenses and sometimes with flash) Only the photographers hired to shoot those evens are allowed to use them.

Depending on where you would sit. If you are right up front, making photos would require less zoom. If you sit far away you would want something that zooms in more. Either lens is fine its how you frame what you see really.

I will answer your question without diminishing the possibility that you may or may not be permitted access to the venue with your equipment.

For concerts (I shoot rock bands), it's best to have the fastest (obviously, more expensive) lens you can afford. Fortunately, your D3100 has some decent noise management with ISO capability up to 6400 (hopefully, you won't need to go that high as noise will prevail).

When shooting the rock bands, I prefer to use Shutter Priority and allow the camera to chose the aperture or ISO necessary to accomplish the needed exposure for the constantly changing lighting.

Set your ISO for Auto, use matrix or center-weight metering (I prefer weighted and set my exposure compensation at -0.7 to assure information rather than overexposure).

Whether or not you will get 'good pictures' is entirely relative to your ability to have enough light to produce a good exposure and the quality of your lens (which wasn't given in your question). I will presume you bought the kit though and in doing so, you didn't get the quality lenses you would have spent more for if bought separately.

"Will I still get good pictures with either lens"? - I have to put this part of your question into proper perspective… Does having a good hammer make you a carpenter?

Whether or not you will get decent photos is entirely relative to your ability to use the tool.
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99% chance that you won't be allowed to take your DSLR in.

This is straight form the BB&T centers website FAQ
source: http://www.thebbtcenter.com/about/faq

Q: Can I bring video or still cameras into the arena?
A: For most events, at the request of promoters, artists and/or leagues, video cameras are not permitted. Regular, non-professional cameras may be permitted-please call 954.835.7000 to inquire about the camera policy for the event you are interested in.

So yeah…