Paris hotels, almost without regard to category or price, observe high and low seasons. These differ slightly from one hotel to another, but usually the high season roughly corresponds to late spring and summer, and possibly a couple of weeks around the Christmas season.
Be aware that when a hotel is listed in any guide or website this will eventually make it a bit harder to get a room at that hotel. That means that you will probably need to book ahead, especially in the high season. However, if they don't have a room they sometimes know another place close by that does have a room available.
When two people are travelling together it can be a much better deal to find a hotel room than to get 2 hostel beds. More privacy for less money.
For individual hotel listings see the various Arrondissement pages.
For those who are staying for a while renting a furnished apartment might be a more comfortable and money-saving option. Furnished apartments differ considerably in quality, so it is important to choose carefully. There are a huge number of websites in the business of helping you find one, but most charge a steep commission of 10% or more. It is also possible to rent apartments for shorter stays, and this is an alternative well worth considering.
Be aware that some agencies, which seem very flexible, actually do not abide by the French law and do not carefully select the landlords and apartments they offer for rent. There are a certain number of guarantees, which are required in France before renting an apartment, and an insurance policy, which aims at protecting the tenants during their stay.
