It depends really. There is no direct bus route from the hotel. You would have to walk to Stillorgan and get the 75 and that would leave you fairly close to the park. Or the 17 bus would leave you in nutgrove/rathfarnham area but you would be faced with a 25+ minute walk to the park. Taxi would be your best bet from the hotel to the gig, but getting a taxi back to the hotel afterwards could be a hassle.