Hi there,
Huaraz is the favourite area to do trekking in Peru as it is known to have the most beautofil mountain ranges and trekking routes. Huaraz is not visited by the tourist crowds, so its off the beaten path.
Where do you want to rent a car? Driving in Peru is not that tough if you know Spanish. Road Maps are rare and road signs are bad so you need to know how to ask for direction and how to handle an emergency case. I always reccomend taking a 1st Class bus or a flight. I assume you will spend time in Lima, thats where you get to see the Pacific.
Hope this helps,, let me know if you have more questions. I work at a travel agency and you can also contact us for more profesional advice and quotes.
Richard
richard@peruforless.com