One thing I have been looking at recently is a certain progression toward samādhi that is found throughout the āgamas and nikāyas.
Especially in the SA and SN, the main meditation framework seems to be (despite its name) the Seven Factors of Bodhi. The basic starting point is mindfulness, and it leads to samādhi, and then equanimity. The Seven Factors tend to presume the Four Bases of Mindfulness, though, and a very concrete path from beginning to end.
However, there are also variants of the sequence that are simpler and found throughout the āgamas and nikāyas. They typically have some sequence like (1) some purity or lofty state of mind, (2) delight in that purity, (3) joy born of separation, (4) pliancy, (5) bliss, and (6) samādhi. The sequence varies a bit throughout the collections, but the last four items listed here are basically universal.
For example, in SA 615, we are given an alternative to the normal practice of the Four Bases of Mindfulness:
Giving rise to a mind of pure faith, recollecting this manifestation of purity, his mind becomes gladdened. Gladdened, there is the arising of joy. The mind being joyful, the body becomes pliant and calm. The body being pliant and calm, the body feels bliss. The body feeling bliss, the mind becomes concentrated.
Because it appears in the Seven Factors and also in many simpler variants, this progression must be quite fundamental to early Buddhism. Still, though, I rarely ever see mention of it. In fact, it seems like the Four Noble Truths and the Noble Eightfold Path seem to get all the attention!
Everyone seems to be interested in meditation, but few people seem to pay attention to the Seven Factors, which are a detailed sequence going from mindfulness to samādhi (plus one stage after).
I think maybe the huge emphasis on the Satipaṭṭānasutta has caused people to believe that mindfulness can possibly not lead to samādhi, or may have some other goal of dry analysis leading to liberation. In the SA and SN, however, mindfulness is very clearly put squarely within the Seven Factors of Bodhi, with no way to skip past samādhi.