If you have top-elite-status for that hotel brand, you still probably need book 1-cat below the suite you are hoping a foc upgrade to, to have a chance. Booking such at hotels with multiple suites increases chance that a)hotel wil upgrade to a suite b)you not some other elite gets one of the possibly available suite upgrades

Each hotel is different, some hotels prefer to reward and upgrade loyalty scheme guests more than 1-cat to a suite, others look to limit as +1cat, resulting in non-loyalty guests who booked a higher nightly rate 1-cat below suite getting a suite of loyalty-scheme-guest booking multiple category below suite.

Most hotels are aware on "big local event" days they will sell out of the lower category rooms, and hold out for guests needing a local hotel to bite the bullet and book the expensive room type such as full suites

Hotels similarly aware on other normal occupancy days with no event to drive rates/occupancy towards 100% and sellout out costy suitrs, that there is a price resistance and that hotel will sellout lower room categories, and have unbooked suites.
So hotel oversells basic rooms, and gives free upgrades to some guests from oversold basic categories

How do hotels decide who to give foc upgrade to , well there is as fairly consisant approach

o Where basic room cat's oversold so upgrades are forced on hotel
a)Give paid rate loyalty scheme guests upgrades first, if necessary moving some guests to suites, could be weighted to guests who booked last and paid most for rooms
b)Give 1-cat upgrade of guests booking highest room types first, freeing up that medium category room to upgrade a more basic booking to. This makes 2x different bookings very happy and hopefully drives repeat business
c)Use NOR1 or equivalent to give guests a discounted upgrade precheckin if suites go unsold
(For IHG, annoyingly IHG Corporate only shows those paid upsells to non-elites !)
d)offer paid upsells at checkin on firstcome/firstserved and only give free upgrades once basic rooms are all occupied

o Where no category is oversold, so hotel is not forced to give foc upgrades
or enough rooms can be freed up without giving foc suite upgrades
a)Reward loyaly scheme guests with 1cat upgrade, as long as not to a premium suite (else such guests will never ever pay such rates)
b)offer paid (upsell) suite upgrades at checkin to all guests.
c)Use NOR1 or equivalent to give guests a discounted upgrade precheckin if suites go unsold
(For IHG, annoyingly IHG Corporate only shows those paid upsells to non-elites !)


Unless an IC brand hotel, I have found that CP/HI in Europe are very resistant to upgrading to the best Suites in hotel, especially as unlike IC's, CP/HI hotels have only 1or2 propper suites at most if any.

Yes if you want a Suite, the old adage is book the room if you really need it, or if confident hotel will have unsold suites, look for an upsell offer(NOR1).
Alternative if have top status is book paid night 1-cat below suchSuite you want and hope you are the elite chosen for such foc suite upgrade. Hotel could well give Suite to a different elite leaving you unlucky.