I remember the 747SP well. Along with the L1011, it was my favorite plane. I didn't like the L1011's shortage of overhead space, though. I flew aboard 747SP operated by TWA and United.

There were 2 economy sections, not 3 like in the 747-200.

One time, there was a China Airlines flight attendant that sat near me who just was aboard for the Brussels-Amsterdam segment of the flight that went on to JFK.

One nice thing was that, with fewer passengers, there was less competition to rush towards customs and immigration and luggage was delivered a bit quicker.

When the 747-400 came out, I was hoping that there would be a 747-500SP but only one such aircraft (sort of) was built and it was still called the 747SP. That plane had the 2 man cockpit, unlike the other 747SP aircraft, but not the new engines found in 747-400 aircraft. The 747SP line was restarted nearly 4 years after the previous one was built. Only one was built for the Crown Prince of Abu Dhabi. The last 747SP was completed in 1986 or 1987.