Just when you thought hostels were already one of the cheapest stays in Europe, one of the top haute hostel chains, Generator, is offering 20 percent off rates at its Paris and London locations. Now through August 31, all you need to do to snag the discount is to book your stay at least five days in advance. This means you'll be able to catch all of those summer festivals and events like the the French Open in Paris and the Wireless Music Festival in London (with beats by everyone from Drake to Avicii and David Guetta).

Don't worry, these hostels aren't your average backpacker lodging, and there are plenty of reasons for adults to  enjoy today's chic hostels  (no, that's not an oxymoron these days). Plus, you can always book a private room with ensuite bathroom for more hotel-like experiences. More about the lovely properties follow below, but first things first: the discounted prices.

We found that rates are best in August at both hotels. In Paris, shared rooms start from €24.80-€28 (around $28-$32), depending on the day of the week, and private twin rooms start from €51.20-€59.20. Private rooms with terraces are just a bit more. In London, shared rooms start from £18.40 (around $29), while private twin rooms start from £33.20-£35.60 (private quad rooms are available, too, from £21.20).

Now through July, we found starting rates for shared rooms in Paris going for €26.40 on select nights, but the prices mostly hover between €29.60 and €32.80 in Paris. Private quad rooms start from €38-€42, while private twins are a bit higher at €63.20-€71.20. During these months, shared rooms in London are mostly £15.20-£18.40, but £45.60 on Saturdays. Private quad rooms likewise are between £21.20 and £28.80, then £49.60 on Saturdays.

More about the hotels: In Paris, Generator opened this spring in the trendy Canal Saint Martin neighborhood in the 10th arrondissement, with views of Montmartre and the Sacré-Cœur from the rooftop terrace. The largest (and newest) property in the chain, the 920-bed hostel boasts private rooms larger than most Parisian apartments -- terrace and hammock included. You'll also receive complimentary amenities like towels, sparkling water, bath products, and WiFi. And when you need a breather from all that walking around town, rest your heels in the Moroccan-inspired chill out area or order a glass of champagne and Bourgogne snails with garlic butter in the Café Fabien, outfitted in original Paris metro tiles.

The London locale near King's Cross was a one-time police section house, whose exposed brick walls and hot-rolled black steel has been incorporated into the hotel in a funky urban vibe. The revamped design is complete with a bus by the bar and an in-house cinema. While the Paris spot has a skysuite terrace penthouse for those who want fancier digs, the 212-room Generator London has private twin room options with en-suite showers and a café serving up typical English fare like fish and chips and London ale.