Rooftop spaces offer views that make for unforgettable backdrops to events—whether they are located in New York City, Toronto, or the Las Vegas Strip. Here are some of the newest rooftop bars, restaurants, and pool decks to consider when planning events this summer.

Atop the Envoy Hotel in Boston, Lookout Rooftop and Bar opened for its second season in early May. (The hotel originally opened in 2015.) The rooftop space can hold standing receptions for 275 guests. The menu may change slightly this year, but current selections for events include tuna tartar, soba noodles, and a charcuterie station.

Guesthouse—a private, rooftop suite—opened at Dream Downtown Hotel in New York in April. The 2,000-square-foot space holds 75 guests for cocktail receptions. Catering options include miniature grilled-cheese sandwiches, turkey-club sandwiches, and quesadillas.

Dream Midtown Hotel in New York will open PHD Terrace—a rooftop bar and restaurant—this summer. On the 15th and 16th floors, the indoor/outdoor venue has an open-air deck on its top floor. Each floor of the terrace can hold receptions for 115 guests or 230 when used together. Inspired by a penthouse patio, the space is outfitted with wood banquettes, hanging ivy vines, and a bar decorated in custom tiles. Menu items include B.L.T. deviled eggs and aged-prime-beef sliders.

The Rooftop Lounge at Thompson Toronto Hotel is undergoing a refresh in time for summer. The infinity pool deck will be resurfaced and the pool area will be stocked with new loungers and plants. The reception capacity for the entire indoor/outdoor space is 238. If used separately, the indoor space can hold receptions for 112 guests; the outdoor space holds 126 standing. Menu items include craft cocktails, jerk chicken bites, and purple kale salad.

After an extensive renovation, the Petersen Automotive Museum in Los Angeles reopened in October. The museum's fourth-floor rooftop can hold 280 guests standing or 150 guests seated. The exclusive caterer for the space is Celestino Drago.

Mr. Purple opened in New York, on the rooftop of Hotel Indigo Lower East Side, in November. With an atmosphere inspired by an artist's loft, the venue has a 3,000-square-foot interior flanked by two terraces. At 750 square feet, the eastern terrace can hold smaller gatherings. The west terrace is 5,000 square feet, and can also hold events; it has a pool, a bar, and plenty of seating. The entire indoor/outdoor space accommodates receptions for 500 guests or seated functions for 100. Menu items include classic and specialty cocktails, flat breads, burgers, and salads.

Chicago's new LondonHouse Hotel is slated to open in late May. The luxury property will have a three-level rooftop bar and restaurant called LH, which will seat 190 guests or hold 300 for receptions. With both indoor and outdoor space, the venue will serve American fare and cocktails.

Mason & Rook, a Kimpton property, opened in Washington in March. The hotel's rooftop pool, set to open in mid-May, will be available for private receptions. It will hold 60 guests for receptions. The adjacent cocktail bar, Radiator, will supply catering; options will include juice bars, taco bars, and an action station serving picnic-inspired fare.

Downtown Grand Las Vegas Hotel and Casino opened Citrus at the Grand Pool Deck in March. At 35,000 square feet, the rooftop space has an infinity pool, cabanas, a full bar, a fire pit, grass seating, and games such as corn hole and table tennis. The venue can hold receptions for 1,200 guests. Menu items include a signature citrus slaw, frozen grapes, and ceviche tostadas.

The Renaissance Chicago Downtown Hotel opened Raised, a rooftop bar, in May. Attached to the rooftop, a 1,278-square-foot event space called Urban Blue can seat 70 guests. Though Urban Blue is enclosed, hosts can leave the doors open so guests can flow between the indoor and outdoor spaces.

The Branksome Health and Wellness Centre opened in Toronto in January 2015. The venue's rooftop can be booked for private events. It seats as many as 70 guests or hold receptions for 110. The venue works with a number of preferred caterers, including Daniel et Daniel and Food Dudes.

The Kimpton Journeyman Hotel will open in Milwaukee's historic Third Ward district this summer. Nine stories above ground, there will be a rooftop bar and lounge called the Outsider. The 5,000-sqaure-foot space will have retractable glass walls and will host events year-round. It will seat 250 guests or hold receptions for 400.