If they are US passport holders then they qualify for visa-on-arrival (100QR by card, 30 days, x1 renewable only). They tell the immigration control they are staying at one of the hotels, it isn't checked. Hotels only require providing visas for _other_ NON-visa-on-arrival nationalities. No need to have them stay at one in this situation. BUT, if they are NOT US passport holders ('passport' not visa or greencard, as greencard means only non-resident visa in their home country passport but able to work in US), then you may have to use the hotel option to get the visas. Many travel agencies can also request the visa with ticket purchase or hotel booking, just be certain they are trustworthy.