It is impressive to think of how many snow-capped peaks are clustered together in this park so close to the equator. Like everyone else we based ourselves in busy Huaraz for access to the national park. There are many options here to visit the park, from multi-day treks to single day hikes, tours or just staring at mountain peaks from your hotel balcony so should appeal to just about everyone that enjoys nature.
Pretty much every hotel and agency offers the same tours at more or less the same time for similar prices. Public transport and doing it on your own generally didn't seem possible or worth the hassle. We booked a few day trips from our hotel and ended up with a different tour company each day. Our first exposure to Huascaran was on our way to Chavin and there is no doubt that the views of the peaks are better from the north of Huaraz (the road to Chavin is to the south). Regardless of tour destination you quickly find yourself above 4000m and the tree line quite quickly which can be hard on some. We stuck to day tours that didn't involve a lot of walking.
One day we went to Pastoruri glacier, a rapidly melting glacier at 5000m. It was a little disturbing to see it dying right before our eyes while people joyfully posed for selfies. We were able to get up close to the very unique and bizarre looking Puya Raimondi plants on this tour.
Another day we went even farther, to see Laguna Paron. It is a popular trip because you can get a view of the mountain supposedly used for the Paramount logo (though from a different angle) and because the lake is a pretty glacial turquoise. I had to seriously question our sanity in going though. With construction on the road north of Huaraz bringing the travel time to 4.5 hours each way, I could see similar sights at home in a closer distance yet would never attempt it as a day trip.
I wonder about the logic of these tours when there are beautiful places closer to town. Our final venture into the park was our most enjoyable. We arranged private transport through our hotel to the trailhead for a hike to Laguna Tambillo (aka Rajucolta). It was about an hour drive and a shallow walk along a little river up a narrow valley for 10km to the lake at the bottom of one of the many glaciers in the park. Because there are no tours here we were the only ones on the trail other than many songbirds and cows. In the end for our group of three it worked out to be the same price for the day as the other tours (there was no entry fee for the park there).