Should he try to sign Nicklas Bendtner permanently?
As things stand, Bendtner is due to play his final game for Sunderland when Manchester United visit the Stadium of Light on Saturday.
The Arsenal loanee has been sporadically successful since leaving the Emirates Stadium last August, but does his form justify the hefty outlay that would be required to sign him on a permanent basis?
On the plus side, Bendtner has settled on Wearside and Sunderland's midfielders have gradually learned how to bring the best out of a striker that can be a real handful on his day.
But a return of seven goals from 30 appearances is hardly impressive, and O'Neill might well extract better value elsewhere for the £6m and £60,000-a-week it would take to secure Bendtner.
If he opts to pursue the Dane, the majority of his summer transfer budget will disappear. For that reason alone, a deal appears unlikely.
How can he add more creativity to his side?
Blackburn Rovers' Junior Hoilett is a target
A lack of goals has been Sunderland's main problem all season, and while the situation improved in the early days of O'Neill's reign, the last few weeks have seen the Black Cats revert to type.
Finding someone to stick the ball in the back of the net is clearly an issue, and whatever happens with Bendtner, O'Neill will be keen to sign at least one new centre-forward this summer.
He could be looking for two if he decides to cut his losses on Connor Wickham, a player who has stagnated this season despite costing £8.1m when he arrived from Ipswich.
A lack of attacking depth is only half of the problem, however, and O'Neill will be equally determined to add some much-needed creativity to his side's midfield.
Blackburn winger Junior Hoilett is a leading target, although Sunderland will face intense competition for one of the most highly-rated youngsters in the country. Also expect O'Neill to be on the look-out for a ball-playing central midfielder.
What should he do with Craig Gordon?
Craig Gordon's contract expires this summer
Gordon's contract is due to expire this summer, and O'Neill must decide whether to offer the Scotland international a new deal at the Stadium of Light.
For most of the season, that looked unlikely, with Gordon struggling to overcome the long-standing knee injury that has restricted him to just a handful of appearances in the last two seasons.
The £9m man was finally given an opportunity to impress in last month's 2-2 draw with Bolton, and he seized his chance to remind his manager why he became the most expensive goalkeeper in British football history when Roy Keane signed him from Hearts.
However, O'Neill will struggle to justify the retention of three highly-paid goalkeepers on the wage bill, and through no fault of his own, Gordon will surely be the odd man out.
Given his status as a free agent, there should not be a shortage of admirers, and it is hard to see him returning to Sunderland for the start of pre-season training.
What other positions need strengthening?
Colback and Richardson have played at left-back
While there is not a need for wholesale surgery this summer, there are other key areas of the squad that O'Neill will be keen to address.
Most notably, he is known to be desperate to sign a natural left-back, having been forced to make do and mend for the majority of the campaign.
Jack Colback, who has played in the position on a number of occasions, is a midfielder, while Kieran Richardson is perhaps a more valuable asset when he is pushed further up the flank.
Wayne Bridge will not be retained once his loan spell expires, so O'Neill will be in the market for a left-footed defender. Erik Pieters has been linked with both Sunderland and Newcastle, but the latter's interest is understood to be at a more advanced stage.
Numerically, Sunderland are reasonably well-blessed with centre-halves, but with question marks over the future of Titus Bramble, and Sotirios Kyrgiakos set to depart, O'Neill could also look to strengthen in that area.
How many players would he ideally like to leave?
Striker Asamoah Gyan is likely to leave in the summer
Cristian Riveros became the first player to leave Sunderland this summer when he completed a permanent switch to Turkish side Kayserispor last week, but O'Neill will be hoping the Paraguayan midfielder is not the last.
Of the players currently on loan from the Stadium of Light, Asamoah Gyan is expected to complete a full-time switch to the Middle East, while O'Neill will be hoping West Ham win promotion and opt to sign George McCartney.
Trevor Carson and Oumare Tounkara will be released as free agents, but the likes of Adam Reed, Louis Laing and Billy Knott would also be allowed to leave after spending the majority of the current campaign away from Wearside.
Beyond that, much will depend on whether Sunderland receive acceptable offers for any of their more valued players.
Ji Dong-won has been a fringe player for most of the campaign, while Ahmed Elmohamady has also been a peripheral presence under O'Neill.