We get quite an odd view of the music of the 1970s based on the bits that end up on 'dad rock FM' - assuming you mean things like Aerosmith, Pink Floyd, Bruce Springsteen etc. Some of these bands had genuine top 40 pop singles; but the 1970s saw the arrival of 'album-oriented rock', which was a radio genre aimed at a fairly young adult male demographic, and which was focused around the then-new FM radio dial, which had superior sound quality to AM radio. A relatively anarchic radio style developed, which was focused around longer songs on rock albums - this was why Pink Floyd had such a hit with Dark Side Of The Moon as an album, or why Led Zeppelin's 'Stairway To Heaven' was so well-known despite being more than 3-4 minutes long.

Actual chart pop in the 1970s was ...about as inane and uncool and contradictory as chart pop in pretty much any time period where there's singles charts (including our own). Some of it was great, some of it was boring, some of it was ephemeral, some of it lasted. Compared to our modern view of it, a lot of it was more folk/country influenced, with the Laurel Canyon stylings of James Taylor or Crosby Stills Nash & Young, or the Eagles and their ilk basically being the tip of a folky/country iceberg. There was also plenty of R&B and dance music - disco - towards the top of the charts. And then plenty of old-style adult contemporary/light entertainment performers. To pick a random year from the decade - 1975 - if you look at the list of #1s on Billboard from 1975 (e.g., on the wikipedia entry here), it's a pretty wide range, featuring everything from Neil Sedaka (who by 1975 was definitely a light entertainment performer) to the Staple Singers to disco stuff like Van McCoy's 'The Hustle' to singer-songwriter stuff like America's 'Sister Golden Hair' or John Denver's 'Thank God I'm A Country Boy'. In terms of Dad Rock FM, the #1s from that year that might still be played on a radio station like that would include, probably (depending on your local Dad Rock FM's programmers), David Bowie's 'Fame', the Eagles' 'One Of Those Nights', and the Doobies' 'Black Water'.

As to frats, and people in colleges listening to pop music/rock music, it's interesting - what college students were listening to in the 1970s has been less discussed than what they were listening to in the 1960s or the 1980s. In the 1960s, college students were associated with the folk movement to a greater or lesser extent, and there was a 'frat rock' movement, as typified by Rhino's (1980s/1990s) Frat Rock! compilation series (e.g,. the 4CD compilation listed here on Discogs) which includes Motown-ish dance tunes (e.g., the Capitols' 'Cool Jerk'), 1960s garage rock (e.g., 'Louie Louie'), and just generally 1960s rock & roll, and Chuck Berry and such things.

In the 1980s, there is clearly a 'college rock' movement, where radio stations aimed at college students shaped the sound of punk/alternative/new wave in the US, with artists like R.E.M., the Replacements, or Sonic Youth benefiting from being played on college rock radio stations that were to the less-popular left side of the dial as people tuned their radios (which is why there's a 1990s Rhino compilation of such music called Left of the Dial), in the years before Nirvana and MTV made such sounds more commercially viable by popularising them in more mainstream outlets.

So the 1960s has college student folk and fratboy rock, and the 1980s has its college rock, but there's less presence in pop music culture of what college students or fratboys listened to in the 1970s (the use of music in movies like Animal House were fairly obviously based on the memories of 1960s college students, featuring the same kind of music, broadly speaking, on their soundtracks as on Rhino's Fratrock! compilations).

As such, I think generally it's likely that those 1970s parties, in general, were focused around album-oriented rock - a form of music of the era that was marketed more to young white suburban males more so than e.g., the disco, R&B or country music of the era, let alone the light entertainment stuff like Neil Sedaka that was marketed to older generations. If we take 1975 as the year we're looking at, it's likely to include popular albums of that general genre aimed at the demographic in that era like Led Zeppelin's Physical Graffiti, Aerosmith's Toys In The Attic, Bob Seger's Live Bullet, Bruce Springsteen's Born To Run.

Additionally, one rock band generally considered a 'party band' in the 1970s in the USA - more well known for their party atmosphere live shows than their hits on the charts - was the J. Geils Band, whose sound at the time was more blues-influenced than you would expect from their later more new-wave influenced 1982 hit 'Centerfold' (their big hit). More representative of their party band sound in the 1970s is stuff like 'First I Look At The Purse', a cover of an old Motown song that might remind some listeners of a more rock'n'roll Blues Brothers.

So most likely, if you're at a frat party at an urban campus in 1975, probably what you'll be listening to is...Bob Seger and Led Zeppelin and Aerosmith and things like that. But of course, demographics are not destiny but instead typically indicate trends; there also may well be plenty of fratboys listening to disco or James Brown or the Average White Band - or punk, later in the 1970s, or who might still listen to the 'fratrock' of the 1960s.

As a follow-up, how would the music be played? Vinyl record players aren't usually very resistant to shocks (from dancing/general rowdiness); the record needs to be manually flipped every 20 minutes (with hands that aren't covered in grease/crumbs/spilled beer); and then the needle has to be carefully lowered back onto the record (which I can see drunk and excited people screwing up royally).

So... cassette tapes? Radio? How would this work in a house party environment?