Hey! that's great idea you must go and do one visit so that you may enjoy the seriene beauty of Divine. Ummmmmm it is awesome!!!

By the time you pay the rental for the RV and campground fees for the places you stay, I doubt that you will save any money.
The way that I have visited the Canadian Rockies several time is to arrive in Jasper by train and rent a car there.
I stay at the HI Hostel SW of Jasper. http://www.hihostels.ca/westerncanada/1478/HI-Jasper.hostel
There are other HI Hostels farther south near Banff.
Even if you fly to Calgary, the convenience of the HI Hostels will sway you away from renting an RV.

How much of your time will you spend in Vancouver? If you can afford it, the quickest way would be to fly from Vancouver to Calgary, and you can get to Banff in an hour or two.

Or, if you drive, you could either (1) drive it in one shot each way, a long 12 hour plus drive without stopping for any of the awesome scenery. And since much of the road is a winding, mountainous, 1-lane in each direction, you will need to add on time for getting stuck behind campers and big rigs.

Or, you can drive it as a 2-day very pleasant tour each way. I fear that will not leave you much time to explore the Rockies in your timeframe, but it would be my preference. If you do have the time and can do that, we'll be happy to help with some suggested routing. It would be less expensive and less stressful (remember those mountain roads) than an RV.

We've always wanted to do the train, but it is rather expensive. And Jasper is less touristy than Banff, just splendid. Of course Banff and Lake Louise are as well. Keep in mind that Jasper is NOT a day trip away from Banff, though - allow about 1/2 day to drive. And you'd be driving along the Columbia Icefields Parkway, so count on lots of picture stops.

Tom's hostel idea sounds like fun.

Do you have two weeks to travel, or is your total trip two weeks with part of that time in Vancouver?

If you only have a few days, it's best to fly to Calgary and drive from there to Banff, Lake Louise and Jasper, then back again for a return flight to Vancouver.

If you have two weeks to visit the Rockies from Vancouver, that's plenty of time for a nice leisurely round trip. Whether you rent a RV, or rent a vehicle to drive and stay at hotels, is up to your preference. Note that the end of June and beginning of July is into prime tourist season, so rates go way up, and any accommodation should be reserved ahead of time. Campground need reservations too. For the mountain parks, check out this website:

http://www.pc.gc.ca/progs/pn-np/index.aspx

For your itinerary, I would suggest taking one day to drive Vancouver to Kelowna (it takes about 4 hours depending on the traffic and most of it is four lane divided highway if you drive the Coquihalla - the quickest route). You may want to spend a day in the Kelowna region - pretty mountainous country along Okanagan Lake and wine growing region.
The next day drive Kelowna to Lake Louise via Roger's Pass, Glacier National Park and Yoho National Park. Lots to see along the way.
Once in Lake Louise, you can decide how to split your time between Lake Louise and Banff (depending on how much time you'd like to spend in the area).
Take a full day (as was already mentioned) to drive up the icefield Parkway to Jasper (that's the winding and very scenic mountain road).
Spend a couple of days seeing the sights in Jasper.
Drive Jasper to Kamloops (5 hours) or Hope (~7 hours)heading back to Vancouver, or drive all the way back if you are so inclined (a very long driving day).

Hope this helps.

Thanks everyone for the replys.They are all very helpfull.
We have been looking at flight prices from Vancouver to Calgary,as we only have time for one week in the rockies,as hoping to spend some time in vancouver with our Son.Need to decide whether to use buses from airport or hire a car as we hope to be there for four days and do Lake Louise and Banff.
Any good suggetions would be appreciated.

You are referring to Calgary airport? If so, get a car. Once away from Calgary, the public transportation options are more awkward, and it's really a car driver's domain. With your time limitations you don't want to spend an undue amount juggling limited public transportations. You will be in Banff in only an hour or two, but it will seem like a world away.

Enjoy! Hope to see a trip report from you.

Flying in to Calgary, rent a car or RV if you enjoy independence in your choices of where/when in the Banff/Lake Louise areas. Borealis has given you a great link for campground reservations, I would add that not all campgrounds accept reservations so that *might* open other possibilities for you to consider. Not sure of your travel dates but note that July 1 is Canada Day, and a very busy long weekend (holiday Monday), for roads and accommodations. Plan accordingly!

Maybe this link will also be useful for more info on camping
http://www.banffnationalpark.com/hotels/bnpcampg.html

I too have a problem trying to fit everything in. We want to go from Vancouver to Quebec - the best and cheapest way seems to be the Canadian (VIArail)but we will only see a very limited amount of the RockyMountains and will miss Banff and Lake Louise is there any way to get there without a car - any buses or coaches or anything!!

We also are visiting friends in London Ontario and need to get from Toronto to London hopefully without flying how long if we hire a car?