Base yourself in Tbilisi's Vera or Marjanishvili
For a budget week, Tbilisi earns three or four nights because the city is compact and cheap to move around. Look at Vera and Marjanishvili, just north of Rustaveli Avenue, where guesthouses and small hotels cluster within a ten-minute walk of Marjanishvili metro. Rates on this site sit in the lower band for the city, and you avoid the inflated Old Town markup. From here, the funicular to Mtatsminda, the Dry Bridge market and Freedom Square are all walkable or one metro stop away.
Stay within two blocks of a metro station on the Saburtalo or Avlabari line and you cut taxi reliance to almost nothing. A single metro ride is paid with a Metromoney card, loaded once at any station kiosk, and the same card covers buses and the cable car to Narikala. Book a room with a shared kitchen if you plan to eat breakfast in; the Deserter Market near Marjanishvili is where locals buy cheese, bread and produce, and it is far cheaper than restaurant meals.
Kutaisi as a second base, not a day trip
Kutaisi, roughly three hours forty minutes from Tbilisi by marshrutka from Didube station or about three hours twenty on the daytime train, suits two nights. Base near the central square or along the Rioni river, where guesthouses sit in the modest band. The Bagrati Cathedral hill and the Green Bazaar are close, and the city works as a launch point for day trips to the Prometheus Cave and Sataplia reserve, around thirty to forty minutes by marshrutka or shared taxi.
Kutaisi also has the cheap flight link to many European cities, so many travellers reverse the route: land there, spend two nights, then take the train east. The train is slower than a minibus but comfortable and fixed-price; book the morning departure if you want daylight over the plains. Skip the evening marshrutka back to Tbilisi if you can, because arrival after dark makes the metro-card setup and finding your guesthouse harder than it needs to be.
Mestia and the mountains on a tight budget
If the mountains are the point, take the night train or a morning marshrutka from Tbilisi to Zugdidi, then a connecting minibus up to Mestia, which adds roughly two and a half hours on a winding road. Mestia guesthouses are the budget mainstay, generally in the low band with dinner included; ask about half-board, because village food is excellent value. Svaneti's trails to the Chalaadi glacier and the Hatsvali cable car are the accessible options without a guide.
Give Mestia two nights minimum, three if weather is uncertain, and build in a rest day for the altitude. The road from Zugdidi is slow and worth doing in daylight. For a one-week trip, I would skip Batumi entirely: the five-hour train from Tbilisi eats a day each way, and the Black Sea resort is at its best in July and August when prices peak. Better to spend that time in Kutaisi and Mestia.
Getting around without overspending
Marshrutkas are the workhorse: they leave from Didube for Kutaisi and from the Ortachala or Samgori stands for eastern destinations, with fares paid in cash to the driver. Georgian Railways covers Tbilisi to Kutaisi, Zugdidi and Batumi comfortably, and the overnight Tbilisi–Zugdidi service saves a hotel night if you can sleep on a train. The Metromoney card in Tbilisi is the single best purchase for city days; load a modest amount and top up at station machines.
For airport transfers, the Tbilisi airport bus to the city centre is the cheapest option and runs through the night; taxis from the arrivals hall are convenient but the fares are negotiable and best agreed before departure. In Kutaisi, the airport is a short ride from the centre. Pack for late spring and early autumn, May, June and September, when trails are open and rooms are not at August rates. Book a hotel with free cancellation and a kitchen, and keep one night flexible for weather.