The outdoors are the whole reason to be here. Hiking trails everywhere—Camelback, Piestewa Peak, South Mountain Park (one of the largest city parks in the country). The Desert Botanical Garden shows you what actually grows here. Scottsdale sits next door, doing the upscale resort thing. Old Town Scottsdale has galleries and restaurants that tourists hit up. Tempe's got Arizona State and Mill Avenue for college bars and cheap food. The food scene got way better—Mexican food is obvious, but there's also James Beard nominees and chefs doing Southwest cuisine that's more than just putting jalapeños on everything. Booking affordable flights to Phoenix makes sense because Sky Harbor is one of the major airline hubs—competition keeps prices down, and direct routes run from most cities.
Hike early. Camelback is the classic—tough climb, killer views. Piestewa Peak is slightly easier. Do these before 8 AM in summer, or you'll regret it. South Mountain has easier trails if you're not trying to prove anything. Old Town Scottsdale has galleries, overpriced shops, and restaurants. It's touristy, but you should see it. Taliesin West is Frank Lloyd Wright's winter home and architecture school—tours run daily if you're into that. Roosevelt Row in downtown Phoenix is the arts district—First Fridays bring galleries, food trucks, and crowds. Crescent Ballroom and The Van Buren have live music most nights. Desert Botanical Garden in Papago Park is worth the admission. Hole in the Rock is an easy walk with solid sunset views.
October to April is when you go—temps in the 60s-80s, perfect weather, everyone's outside. November through March brings the cheapest flights to Phoenix outside holidays. May and September are tolerable if you get deals. June through August is hell—115+ degrees regularly. Only go then if you're staying by a pool or got a screaming deal on hotels.
Sky Harbor Airport sits right in the city, maybe 10 minutes from downtown, depending on traffic. Light rail runs to the airport for cheap. Rideshares cost $15-30, depending on where you're going. For cheap flights to Phoenix, stay flexible with dates and compare everyone. Midweek flights cost less, and off-season (summer) has deals if you can handle the heat. Phoenix isn't pretty, but the desert is. That's enough for some people.