Chord progression vs melody line to determine tonality

[armans]

Not sure if this is the best place to ask the question but here goes anyway. I am trying to understand the relationships between chord progressions and melodies and am writing some music and came across some interesting chord progressions that left me scratching my head. If I have an ambiguous chord progression like lets say

G Em Bm Bm

Whether the sequence is in G major or Bm (natural) is unknown as the chords belong to both keys so if I write a melody abstaining the use of the C# note then the melody too would be ambiguous so the tonal centre would still be unknown. So my question is, would the note I choose to end the melody help determine what the tonal center of that part of the song is? For example, If I ended on F# then wouldn't that mean that the tonal centre of the song is more leaning towards Bm as opposed to Gmajor since the F# is a leading tone in G major and a melody wouldnt resolve there?

[shufflebeat]

It depends on whether resolution is the goal, F# being the ∆7 of G.

This is a little bit like planning your family holiday by looking at a roadmap. There are those, of course, who see no problem with that but I would suggest they just like roadmaps more than family holidays.

Some genres are very respectful of the literature and I think this is what you're alluding to but it would be easier to judge if we knew more if the context.

[GilesAnt]

Absolutely agree with shufflebeat

Worry about the theory later, at this stage there is nowhere near enough information to decide, and anyway don't let your music be theory-led.

What would be the benefit to you of knowing what key it is in - are you looking for related chords, or are you seeking to keep your melody with in a pre-conceived tonality? Tonal ambiguity is well worth exploring in its own right.

[Tomás Mulcahy]

This is a little bit like planning your family holiday by looking at a roadmap.

Brilliant analogy

[Drew Stephenson]

To be fair, that sounds like a pretty good way of planning my holiday actually!