A lot of researchers use MTT as a viability/toxicity assay depending on the formula employed. Technically, it is more relevant to understanding how metabolically active your cells are since it works on converting MTT to formazan crystals which are dissolved in DMSO, and absorbances are read.

I used to conduct a lot of cell architecture and mechanic studies during my doctoral program. Having worked with multiple forms of scaffolds ranging from 2D to 3D cultures, I would suggest Live/Dead staining kits which use calceinAM and ethidium-homodimer for calculating cell viability. As for cellular architecture studies, you can use any form of actin stains (phalloidin for instance) along with DAPI stains to characterize the nuclear orientations. There are a lot of tools available out there which can help you further quantify these architectures. Here are some references from previous collaborative work and these papers are available on researchgate for you to download.

Article Valve interstitial cell shape modulates cell contractility i...

This one uses matlab to characterize the cellular shape and architecture.

Article Valve leaflet‐inspired elastomeric scaffolds with tunable an...

This one uses alamarblue assay for cell proliferation studies and ActinGreen for cell architecture staining which was analyzed using ImageJ. Might be easier if you don't want to use matlab but this only does minimal analysis.

Here is another article published by a friend that focuses on studying cell migration. Article Cell Migration and Breast Cancer Metastasis in Biomimetic Ex...

Lastly, I would suggest that you find out what are the available resources/equipment that you have access to before designing these studies. If you are using fluorescence microscopes, find out what channels and filters are available which can help you choose your stains. Hope this helps!