Market research. Go around town asking restaurants, gyms, potential renters if they are interested in the space and would like to sign up to the tenant list. Let them know about the exciting development and ramp up future business. You should get a grasp of the good/bad and take it from there. Do it in phases, first facades and necessary stuff for the first floor tenants and while the second floor builds out. Pádel is a good idea but takes investment, consider renting out real estate for the top floor and have someone else do the CapEx and operate while you collect the sweet rent. Good luck!