We go to RMNP almost every year to hike. We have rented 4 different houses/cabins in Estes Park via VRBO. go to www.vrbo.com to see if there is anything that fits your needs. Make sure any thing you consider has lots of reviews as this is a "buyer" beware situation (VRBO is just a listing website, they don't verify or promise anything).

Our main activity when we are there is hiking. We also usually drive up Trail Ridge Road once while we are there. The hiking is really great as there are trails for all levels of fitness and interests. The various trailheads can be busy - so some planning should be done of where and when you want to hike.

We stayed here at Antlers Point. On the main road into RMNP Fall River Entrance about 5 minutes. About 15 minutes to Estes Park for shopping or lunch/dinner. You want a cabin away from the road as early morning cars can be noisy. If anyone in group has a Handicap placard bring it as most of the parking spaces are gone by 9:00am except the Handicap ones.

Also, you will have to pay to get into the park everyday unless you have a Park Pass, or a disabled Vet (have to get pass in advance from another Federal Park.) Sprague Lake is my favorite. Nice easy level hike around a shallow water lake that usually has a Moose in it. Picnic tables nearby.

FYI no Verizon cellphone coverage in Park so be prepared to make advance meet up places and times if separate.

http://www.estescondos.com/antlers/index.html

You can fish on the property without a license legally and we caught several nice size trout for dinner.

We looked at these and liked them.
http://www.streamsideonfallriver.com/SS-GalleryWildlife.HTML

Four days is a nice amount of time to visit Estes Park and RMNP, and July, although popular, is a good time for warm daytime temps with a daily chance of afternoon thunderstorms- be sure to plan most of your hiking in the mornings.

The information above isn't quite correct about paying every day to get into the park... the regular RMNP entrance fee is $20 per vehicle and allows you seven consecutive days of access. Also, I've found you can get cell phone coverage in the parts of the park closer to Estes - just depends if you're up high or in the valleys.

We are frequent visitors to Estes Park and love to stay at the Woodlands on Fall River Road. They have two-bedroom condo-like units in a beautiful location, very clean and comfortable with decent size kitchens, wood fireplace, balconies or patios and friendly management. Only a 5-7 minute drive in either direction to get to the park or to the main part of Estes where most of the restaurants and shopping can be found. There are many other inns, cottages and condos on Fall River Road, so that would be a great place to start to look for lodging.

I hope you enjoy your trip to one of the most scenic areas in the Rockies!

Are you aware that if you are 62 you can purchase a lifetime National Park pass for $10? It's the best bargain in the country, IMO. The pass enables you to any USNP fee areas for free, along with 3 others in your vehicle, who need not be seniors.
I agree with others here that the road to the Fall River Entrance is a very good area to stay; lots of lodging, less traffic.

tekwriter, thanks for the correction-thinking of another Park.

Thank you very much, everyone for your helpful replies. I will look into the places mentioned, and am glad to know that the 4 night visit is adequate time to see and do. Are there particular sights, drives, or hikes that you feel are 'not to be missed?'

How much of a hike are you looking for? Hikes in the park range from super easy (flat, under 0.5 miles) to extremely strenuous.

Drive up Trail Ridge Road and over to the west side one day. Do that early in the day - July will bring almost daily thunderstorms in the afternoon and it's not much fun to be driving Trail Ridge Road in a thunderstorm. You can spend some time in Grand Lake and on the west side then make your way back to Estes Park later in the afternoon, just watch the weather.

Bear Lake Road will be under construction again so I'd assume it will be closed to private vehicles every day between 9am and 4pm just like last summer. If you want to go to Bear Lake, Alberta Falls or Sprague Lake (or anywhere else along the road) you'd want to get there as early as possible or wait until evening. Before 8 am for sure, probably even earlier or the parking lots will be full and you'll have to take the shuttle.

http://www.nps.gov/romo/planyourvisit/bearlakeroad_reconstruction.htm

Estes Park is a pain to drive in and find parking when it's busy, so if you think you'll spend a significant amount of time shopping or wandering around downtown, you might want to look for lodging that's within walking distance of the downtown area. Or park before you hit the worst of the downtown congestion and walk from there.

Depending on where your lodging is and what time of day you get going, it can be faster to drive through town and enter the Beaver Meadows entrance on the day(s) you want to drive down Bear Lake Road. The Fall River entrance means you have a fairly long/slow drive through the park to get to Bear Lake Road. It really just depends on how close to downtown you stay and whether you can get going before traffic picks up.