In 1964 Fred Pontin of Pontin Holidays opened Cala Masqueda holiday camp on the north east coast of Majorca and I remember standing on one of the fingers on a Saturday in the late 1960s at Gatwick watching Spantax DC-7Cs arriving/departing to Palma taking holidaymakers many on their first trip abroad. C-990s started to take over the operation a little later on.
Saw a TASSA Dc-7C at Castle Donnington (EMA) on a Sunday in August 1968 while on a pit stop travelling from Bedford to York on the M1.
Only Spanish charter airline I have flown on was an Aviaco flight to Palma in 1963 from Manchester but it was operated by an Iberia Super Connie so don't know if that counts but the airline ticket does say Aviaco on it. That was with Wallace Arnold Tours to Can Pastilla. I think it was £30 full board for two weeks with own shower and toilet. Great memories.