Santo Domingo de los Colorados is a strategic point for travelling all Ecuador. The road from Quito to Santo Domingo goes through tropical forests, and crosses rivers with beautiful waterfalls. There are highways and bus services from Santo Domingo in all directions: to the coast (Manta and Portoviejo), to the north (Ibarra, Tulcán), to the capital (Quito), to the south (Ambato, Loja, Machala). The name of the population came from the Tsáchilas Indians that lived originally in this area, that had the custom of painting their hair red with vegetable extracts. It is an agricultural area, mostly dedicated to banana plantations, sugar cane and palm. It is also a beautiful town. It has a tropical climate, and some very nice hotels. I stayed at the Hotel Casino Zaracay, that has a beautiful park, with a small bird zoo and casino. It is a 4-star hotel and a nice place to stay.
The road from Quito to Santo Domingo is charming. You go through the Andes and down to a more tropical area. There are beautiful waterfalls in the mountainside, and it is a short trip (about and hour and a half). The road from Santo Domingo towards Portoviejo (an old colonial city) and Manta is full of banana plantations, although the main banana producing area is Machala, further south. The countryside is full of plantations on the mountainside. Although Manta has nothing special to offer regarding beaches, you will certainly enjoy the trip. You will enjoy your stay at Santo Domingo, and from there you can go to the coast (Manta, Esmeraldas, Guayaquil, and probably Salinas), to the border with Colombia (Tulcán, just in front of Ipiales), or to Cuenca and further down the border with Peru.
You can use Santo Domingo as your strategic base for visiting the whole country without changing hotels every day. The trip to the north will probably take some 4 hours, and there are very nice places far nearer (for example to buy leather articles in Otavallo). I really enjoyed my stay at Santo Domingo de los Colorados. It is a small town, but a very active strategic point in Ecuador. You can buy handcrafts on the street (mainly colorful Ecuadorian clothes) Give Ecuador a try; you will not regret it.
The road from Santo Domingo de los Colorados towards the North passes through beautiful places like San Juan de los Lagos and Ibarra, continuing to the international border with Colombia at Tulcan. There is a waterpark on the way up with a huge water slide. Ibarra is in front of a lake, and is a nice city to visit. And Tulcan is on the international border, and nearly forms one city with Ipiales (Colombia) from where you can continue travelling through Colombia towards Pasto, Popayan, and Cali. One word of caution, however. Travelling by road from Pasto to Cali is not recommended, it is (or used to be) a guerrila controlled area. It is better to take the plane from Ipiales or Pasto to Cali and then continue your travel by road or plane.