Vegas
 

We would like to visit Vegas in January. We are a family of four with two older teenagers and two young seniors. How long should we stay and does anyone know where we could find a good flight and hotel deal?

I would be worried that teens don;t have enough to do - since they can;t go into the casinos and Jan is way too cold for swimming - the pools are closed. Also - even day trips - esp Grand Canyon - also take you into cold weather and possibly snow - for whatever is left open.

Depending on where you are coming from Allegiant has some combination deals that are hard to beat. http://www.allegiantair.com/
If you rent a car you can drive out to Valley of Fire, Hoover Dam and Red Rocks on day trips from LV. If the Grand Canyon is snowed in, you could try a night in Death Valley NP.

<<How long should we stay and does anyone know where we could find a good flight and hotel deal? >>

Way too general of a question. What do you want to do while you are there? That will affect the length of your stay. I would start with Kayak.com to get a sense of some of the air/hotel packages. Not sure if budget is a concern, but you will get significantly better deals if you travel Sun-Thurs.

We were thinking of staying 4 to 5 days.

Is your intention to stay IN Las Vegas for 4-5 days? Admittedly, I only like Vegas for 1-2 days every 10 years, but trying to set my lack of objectivity aside, I definitely do not think there's enough to do there for more than a couple of days in the winter with teens.

Although I enjoy Las Vegas (just got back from a 4 day stay), I am not sure what the teens would do for 4 days during the day in the winter (no pool time). Admittedly, I have never gone with kids so maybe others who have are more knowledgeable. I think if you plan on taking day trips out of Las Vegas (Hoover Dam, Red Rock Canyon, Grand Canyon), then it might work.