First…. I wish I knew what a pannier was…….
Buying from a dealer sounds like a good option for you. If you do not know what to look for or are uncomfortable in your judgment and do not have someone that you trust to walk you through a dealer would be a best option. Sometimes you will find bikes there that still have warranties, or even the dealer may offer one in house. It will also give you the chance to look it over and ask lots and lots and I say again as to drill it in…. ask lots of questions.
As far as cruisers being a first bike, there is absolutely nothing wrong with that. I started on a Vulcan 500 and have since moved up to the 900 classic LT…quite a few of us on here started on cruisers. Actually in some instances cruisers are better as they are meant for cruising and not so much performance—in the way of speed and flash. Cruisers typically have a lower center of gravity then sport bikes but not always the case. Also the power distribution is alot different.
Oh just looked up pannier…..lol… I call it a saddle bag…as long as Google got it right. Those you can also find for almost any bike both in “soft” and “hard” versions. For sport or cruiser.
Go out to your dealer… ask to see the used bike…sit on some. Find whats comfortable to you. Me personally I sat on a few and even took the time to do a very slight lean from one side to the other, not so much in knowing you may drop it right there in house, but enough to allow yourself an idea of how heavy it will be and how balanced it is.
Browse through some of Ben’s reviews and see which ones sound great to you. It’s a good starting point. All in all the best bike is going to be the one YOU feel comfortable and safe on.