I'm not that sure about these names. They have potential, but they certainly have weaknesses too. It depends very much what you plan to do with them.  Some issues with these domains and potential businesses using them :

First - in my extended experience most students are loyal first and foremost to their named institution e.g. Edinburgh or Herriot Watt or Napier or GSA or Glasgow or whatever and not more generically to their city and being a student there ... in Manchester there are quite a number of HEIs and personally I don't think students at UMIST, Salford, MBS or RNCM would necessarily empathize with the title ManchesterStudents. And then the two others with Manchester in the title would find it too much of a hybrid for their liking.

Second - and this may depend what you have in mind for these businesses - you may come across an understandable defensive or even protectionist attitude from the Universities, the Students' Unions and Guilds, the NUS and area NUSs. They each operate as businesses or even groups of businesses and in some cases they have quite developed and commercially minded web strategies. In some cases they may be among the most successful and substantial catering and entertainments businesses in their own town.  Resistance to private student-targeted papers, magazines, calendars, diaries and handbooks and even alternative rag mags has been a fact of student union life for decades. Web sites just a new twist.

Third - here may be an element of risk, partly fuelled by these kinds of issues - that advertisers and potential partners could prefer to stick with the student/institution owned media outlets.

Fourth - students will 'admit' to being students in various ways, but they do not necessarily want to define their lifestyle and their lifestyle choices by this term. Buying into a website with 'students' as the main signifier may not be a natural response for these young and not so young people. Similarly many businesses will blatantly go after students "Students Night, #1 a pint, Tuesdays" etc etc but the cool students will not necessarily be regulars, and the coolest business may go for this discrete market directly but without the label. 'cool' doesn't necessarily pay the rent any more than 'naff' doesn't.

Fifth - there are always issues about starting essentially 'local' businesses from a remote and centralized base. Basically there could be a feeling that your operations are carpet-bagging, or more easy to counter, out of touch.

Sixth - there are a number of similar generic domain names and/or complex URLs which could compete in the same business area if there is really a business there. Someone somewhere owns students.com and there are lots of possibilities with hyphens, underlined spaces, word order, other domain types - meaning you wither buy up hundreds of permutations or you prepare to be the early adopter who either flies or drops like a stone when the followers learn from their mistakes and get easier technologies to work with.

Seventh - and I'll stop here - if this were structured so that there were local teams to counter issue five there would be problems of scale, communication, duplication.

I'm not trying to poor cold water on these domains which surely do have more value than their cost to you but I do think that unless you can come up with good answers to these issues, or a compelling unique and protectable content idea which makes the sites work (whatever their names are) you may be better off selling them in some way to the various student unions and organizations in these cities.  Whatever potential value they do have may well be much easier for these insiders to unlock than for you in terms of local knowledge, legitimacy, access to low cost workers and so on.