Words beginning with T that could be substituted for good would depend on the context, but some possibilities are:
centimeter centennial
divided
Some words beginning with 'bi' meaning two are: biannual, bimonthly, biweekly, bicentennial, binary, biathlon, bisexual, biped, and bipartisan.
stellular, stelliferous,.....i guess there are more but i don't know them...
Some Spanish words beginning with "g" are gato (cat), gracias (thank you), buena (good), grande (big), gusto (taste).
Some positive words that begin with the letter P:perfectphilanthropicpoisedpowerfulpragmaticpreciousprettyproductiveprofessional
nice,good job,sweet,awsome,
Some four syllable words beginning with U are:UnderstandingUnicycleUnluckily
octupus october [ originally the 8th month in the Roman calendar ] also, octagon, octet
Some positive words beginning with M are:melodiousmerrymildMargaritamannerlymommymagneticmemoriesmassagemellowmanageablemarigolds
Some words beginning with 'sub' are:subjectsublimesubmitsubmarinesubletsubterraneansubmersesubsistsubservientsubduesubliminalsubmerge
How about: earth, soil, ground... ? Is that good? Hope I helped!