In the end, in a dramatic finale at Celtic Park, they fell just short as Leinster made it two Guinness PRO14 titles in a row.
But what a campaign it was from the men from Scotstoun – they finished the regular season in ridiculous form with eight wins on the spin.
That sealed top spot in Conference A for the second season in a row, holding off an in-form Munster side in the process.
But in the Final Series, they came unstuck on home soil against Leinster and next year, will be desperate to finish the job off.
It’s not hard to see where Glasgow Warriors are strongest.
Their array of attacking threats in the 2018-19 campaign made them nigh on unstoppable when in the mood.
Leinster scored the most tries, but Glasgow were close behind in second and when it came to creating something from nothing – no-one did it better than the Warriors.
They made more clean breaks, beat more defenders, and carried for the most metres overall of any team in the entire league.
Areas to improve
The key work on for Rennie this summer is undoubtedly going to be the set-piece.
The scrum, in particular, was an Achilles heel for the Warriors during the regular season.
Their success rate on their own scrum ball was only 87.7 per cent – the worst in the entire league and prop Oli Kebble was the second-most penalised player in the whole of the Guinness PRO14 as well.
The lineout didn’t fair much better, an 87 per cent success rate only good enough for tenth in the league.
They probably fell off a couple too many tackles as well, their completion rate of only 87.5 per cent also down at tenth in the league.
Winning at the RDS Arena near the end of the regular season was an indicator of how far Glasgow have come this season.
Their 39-24 triumph – inspired by a superb tackling performance from Jonny Gray – was their their first over the defending champions in Dublin since 2011 but that was a Leinster side shorn of some of their biggest names.
So the real high point for the Warriors has to be their semi-final shellacking of a fully locked and loaded Ulster side at Scotstoun.
The Scottish side were on top of them from the outset, Ali Price and Adam Hastings pulling the strings in delightful fashion as they put a half-century of points on the men from Belfast.
It was Stuart Hogg’s final game on home soil and he signed off in style, while Rory Best’s last match in an Ulster shirt was not the valiant victory he might have hoped for.
Hard to know where to start here, as so many players came of age under Rennie this year.
Adam Hastings won the Guinness PRO14 young player of the year award and in his first season after the departure of Finn Russell looked the heir apparent at No.10.
But he was something of a known quantity already for the Warriors – winning his first Scotland cap’s last summer.
But Kyle Steyn and Stafford McDowall both looked like brilliant arrivals in a crowded Warriors midfield.
Steyn can also play on the wing but alongside Sam Johnson, kept Huw Jones out of the starting midfield for the season run-in.
And McDowall looks to have replaced Alex Dunbar as the next big thing in the Glasgow centres with a promising first campaign.
And a word too for lock Scott Cummings, who has even caught Gregor Townsend and Scotland’s eye with his performances in the engine room.
The aforementioned Hastings and his half-back partner Ali Price were the key cogs in the Warriors impressive attacking game plan.
And in a season where Price also leaped ahead of Greig Laidlaw as Scotland’s starting No.9, it is hard to overlook the scrum-half.
But the Warriors impressive regular season finish is predicated upon role players who chip in when the internationals are away.
And no-one epitomised that more than Rob Harley, filling in at both second and back row for the Warriors and leading by example.
The tackling machine made the tenth-most tackles of any player in the entire league across the regular season and was recognised by his Warriors squad as the Players’ Player of the Season as a result.
Next year, Rennie was looked for evolution rather than revolution.
Stafford McDowall, Jamie Dobie and Kyle Steyn all will join the first-team squad for their first full pre-season and entire campaign.
Another familiar face in lock Andrew Davidson is re-joining from the relegated Newcastle Falcons to provide second row competition.
And then, a couple of young props in George Thornton from Wasps and Charlie Capps from Stade Nicois are also arriving at Scotstoun.
No doubting who the key departure is – Stuart Hogg will take some replacing at Scotstoun.
Glasgow’s first-choice full back for the best part of a decade, Ruaridh Jackson and the rest of the back three have big shoes to fill.
Up front, they are losing Jamie Bhatti to Edinburgh, while in the backs Alex Dunbar and Lelia Masaga are moving on.
Also moving on are Kevin Bryce, Lewis Wynne, Robbie Smith and James Malcolm while Brian Alainu’uese has already departed.
Glasgow have revealed their new club badge!