The Marriott Bonvoy T&Cs treat "enhanced room upgrades" the same for Platinum Elite, Titanium Elite, and Ambassador Elite. The wording for Gold Elite is similar, but "standard suites" are not included.

I would like to think that well-managed properties with properly-trained employees take Marriott Bonvoy tiers into consideration when assigning rooms ahead of time and in how the front desk deals with arriving Elite guests:

Non-member < Member < Silver Elite < Gold Elite < Platinum Elite < Titanium Elite < Ambassador Elite

A property can, of course, take other factors into consideration, such as higher room rates or major corporate accounts. Interestingly, the two are at odds with each other. The rates for major corporate accounts are typically lower than the common rates at Marriott.com (such as non-refundable advance, regular, Member, AAA, or Senior).

Alas, "hit or miss" probably describes it best for many properties.