What angle can best generate user emails for a unique short term rental site?

This is the kind of question I usually get by most of my clients and love the opportunity to help with a few ideas. Since you are planning to offer the spaces mainly for art events, meetings and popup shops, you are mainly targeting locals rather than tourists in the first place. So I would focus on those clients first. Start using local social media and invite people to a cocktail on one of your spaces. You can either have a mini showing, art-gallery style. Go to the office buildings in the city and invite the employees. Show up at artists' coops and handle invitations to your cocktail. Go to the places your users already are. Once in the cocktail collect the information of those attending and ask them specifically what use they would give that space (meetings, events, etc.) Once you have filtered their responses you can email them with specific tips and suggestions on how to discover the best spaces the city has to offer for their specific needs. You can even sponsor a local, up-and-coming artist and offer invitees to let them know when the artist would do a popup shop in one of your spaces.
We can definitely brainstorm more about this if interested
Good Luck
Elba Nino

what i would do if i were you in a list :
- asap targeting your end-user that could be transit people like foreigners within meetups or interested in events or wework spaces e.g.
-digital media is the key: get a 10 min coffee and network about why you are differentiating yourself.
- and sample stuff like no others. Go to NYC and create a meetup or find embassadors and pay them a commission for example.