I'm planning a trip to the Yellowstone area for two weeks this summer. My parents (seniors in good health), my 9 year old son, my spouse and myself are flying into SLC, renting a car, and heading to Tetons/Jackson for 3 days, then to Yellowstone for 3-4 days. We're not sure if we should attempt to go all the way to Glacier or not. My son really wants to see snow (we live in Florida). Any helpful advice is appreciated. This is a big trip for us and don't know when we will be in that area again.

Having visited all of the parks you mention, I find something of wonder and beauty in all of them. It is a long drive from Yellowstone to Glacier, but that trip, too, can be interesting.
Out of the two weeks you have planned, you indicate that a week of it will be in the Tetons and Yellowstone. If you do not go to Glacier, where will you be on the other 5 days? (I am assuming 2 days of the 14 for travel to and from SLC.)
There are two basic ways to do drive from Yellowstone to Glacier.
1. Drive through Great Falls.
There are two relatively direct routes you can take to Great Falls: (a) take US 89 from Mammoth Hot Springs through Livingston to Great Falls, or (b) Take US 287 from West Yellowstone north to I90.
Then go west to state route 69, then north to I 15.
On both routes, go north from Great Falls on I 15 to exit 348. At this point turn east through Valier and join US 89 to the west. Follow 89 on to Glacier. (Alternatively, you could stay on US 89 out of Great Falls. The Interstate is faster driving, but a tad longer.)
2. Join I 90 and and follow it east until you reach US 93. Take 93 north to Polson. In Polson, you have a choice. Stay on 93 to Kalispell or take state 35 along the east side of Flathead lake. Neither way is a fast route, despite the high speed limit!!
There are more motels around Kalispell and Whitefish than there are on the east side of Glacier, but prices reflect the growing popularity of Whitefish.

From West Yellowstone to Kalispell you have about a 400 mile drive. I figure it will take you close to 8 hours to do it.

The amount of snow you will see in Glacier depends on how late in the year you go. If you are there in early July, there will be snow close to the roads, usually. If you are there in late August, much of the snow will have melted, although you can still see patches on the mountains.

I think the Sun Road from the east to the west side of the park is a spectacular drive. There are quite a few very nice mountain drives in the US, and that is one of them. Glacier is mostly a hikers park. To see the really beautiful sights, you must take to the trails, but that does not imply that you cannot get an eyefull from the highway.
If you have time, take at least a short stroll along the Garden Wall from Logan Pass. If you can go as far as a prominent feature known as Haystack Butte, there is a good chance of seeing goats, big horn sheep, and marmots.
Good luck with your planning.

Bob has given you excellent advice. Just a few more notes for you. In July in Yellowstone you can probably travel the Bears Tooth Pass and your son will most likely see snow there. The pass is spectacular and you can then stay in Red Lodge (I like the Yodler Motel) which is a great little town. Not far from Red Lodge (about 10 minutes) in Bear Creek is a bar that has w/e pig races which are really fun - your son (and you) would probably enjoy them greatly. You can also visit Cooke City on the edge of Yellowstone which is also very small and has quite an old time Montana flavour. We always stay at Hoosiers Motel - it is very small and basic but bar none, one of the cleanest places I have ever stayed. The owners are great.

It has been two years since I was in Cooke City or Red Lodge but at the time we were there we found the travelling in Yellowstone to be a bit hazardous as the roads are not maintained very well. According to the residents of Cooke City, there has been some problems with the Parks Service funding repairs. I doubt this has changed much and you should really watch for HUGE potholes in the road.

If you do plan on going to Glacier, be prepared for a very long day's drive. Montana is a big state. Take Bob's suggestion as to routes. There are some that are more scenic from Great Falls to Browning, MT but you need to know the state well and you could get lost. I like the town of Choteau and not far from there, if you are into the bizarre, the town of Bynum where there is a pub called Katie's Wildlife Sanctuary. We have had lots of fun there but the people are definately unique.

If you do decide to go to Glacier, be sure that you book your hotels well in advance. Kalispell, Whitefish, Bigfork, Columbia Falls, all fill up in the summer. In Bigfork, a decent motel is the Timbers. It is close to the lake and within walking distance to the town itself. Bigfork has the Bigfork Summer Playhouse and they offer 4 plays per year and it is a fun time, although expensive as is everything in the Flathead Valley at that time of year.

Definately do the drive over the Going to the Sun Highway if you go to Glacier. For non-experienced mountain drivers, it can be a bit scary but it is indeed beautiful.

Have fun.

Thanks for the advice. Our trip dates are June 19-July 3. Maybe we will drive the Bear Tooth Pass and hope to see snow there. Mom wants to go to Red Lodge. I'm not sure I want to travel another 8 hours north. We'd like to see the area of Montana just north of Yellowstone and also go to Cody. Do you think Thermopolis is worth a visit?

Take some warm clothes and rain gear. We were there in July and it rained for 4 out of 6 days. We even had snow in Yellowstone. Didn-t ruin the scenery though.

Rayna: take from me, you have gotten excellent advice from the others who have posted. (I will not be so presumptive to say that my advice is good. But I have been there.)

We stayed at the Timbers Motel in Bigfork 18 months ago. It is quite acceptable. The main part of town is interesting with live performances at the theater, and the usual tourist type
shops. If you possibly can, try to stay one night in the park itself. Lake McDonald Lodge on the west side is acceptable, with allowances!
Big Fork is a ways away. I think it is too far for a base of operations for a multi day visit.

One thing about Choteau. I don't know if you are into dinosaurs, but Dr. John Horner of the Museum of the Rockies in Bozeman has done considerable research near Choteau and has advanced our knowledge of how dinosaurs cared fo their young.

The Bear Tooth Pass is great. If it is open, that is another way you might drive to Glacier, but it will take you longer because you are increasing the distance. From Yellowstone, use the northeast exit to Red Lodge.
My son likes the Yodler Motel. He says it is affordable and yet comfortable.
From Red Lodge, you could hit I 90 and to west until you turn onto I 15 north. Or you can strike out across country to Great Falls. I took the "back route", but you need a good map to do it.

But, yeah!! if you could get in both the Beartooth Pass and the Sun Road, you will have traversed two of the most scenic mountain drives in the US.
(Trail Ridge Road in Rocky Mountain NP is another; as is the drive from Ouray Colorado to Durango. And then there is Tioga Pass over the Sierra into Yosemite NP.)
Just as word of caution, however. I think 3 days for Yellowstone might be cutting it close. I can spend 3 days in the geyser basins alone. In fact, I hope to do just that in May. I have 4 nights in the park and I know geyser sitting and watching will be tops on my list. Even with a 9 year old, if you have a full moon, you might find watching one of the big, semi predictable geysers erupt by moonlight.
My wife and I did, and even after 42 years of being together, it was a very nice moment. Something about a full moon!!
At any rate, have a wonderful trip.